Optimum tyre pressures and tyre types for electric vehicles: One-click survey #21

Your take-home messages:

Only a third of EV owners follow best practice guidelines of checking tyre pressures at least once a month.  The remainder are likely to experience reduced range on full charge, reduced energy economy (km/kWh) while driving and increased tyre wear. In extreme cases, driving safety may be compromised.  Low rolling resistance tyres will extend range.  There is a need for effective educational campaigns to improve tyre care practices amongst both EV and Internal Combustion Vehicle owners in New Zealand.

This month’s poll:

We wanted to collect information on what tyres are currently out there, how often their inflation pressure is checked and adjusted, and what drives tyre replacement choices. Our aim was to help make your tyre decisions easier when it’s time to replace, and to share some hot tips on best pressure practice to delay that need for replacement as long as possible.

Accordingly, our twenty-first 1-click survey began by asking respondents to choose between five options to complete the following statement: “On average, I check and adjust my tyre pressure”

1. Weekly
2. Monthly
3. A few times a year
4. Once a year
5. Never, my mechanic does it

Respondents could then add comments and provide answers to five open-ended supplementary questions:

1. “What determines your frequency of checking tyre pressures?”
2. “How do you decide what pressure to use?”
3. “Compared to your current/previous Internal Combustion Vehicle, has your frequency of checking tyre pressures changed? And if yes, how?
   • About the same
   • Less often
   • More often
   • Other
4. “What sort of tyres do you have on your EV?”
   • Known brand
   • Unknown brand, but factory-fitted/originals
   • Unknown brand, but low rolling resistance/eco tyres
   • Other
5. “What determined your choice of tyres?”

The poll was sent to 889 participants in Flip the Fleet on 25 May 2018. We received 512 responses by 13 July 2018 and 368 of them included detailed comments and answers to at least one of the five supplementary questions.

Frequency of checking and adjusting tyre pressure

About a third (36%) of EV owners check and if necessary adjust their tyre pressure at least each month, the recommended frequency to maximise energy efficiency and safety.  Over half of respondents (58%) checked and adjusted their own tyre pressure a few times or just once a year. Around 6% indicated they never checked or adjusted tyres themselves, leaving it to their mechanic to do it

 

Figure 1.  Frequency of checking tyre pressure by electric vehicle owners.  The percentages were calculated from 512 responses from throughout New Zealand in July 2018.

 

Many of the owners that check their tyres most regularly have: (i) a Tyre Pressure Monitoring System (TPMS ) on their dashboard or receive a similar warning signal through LeafSpy; (ii) have set up routine tyre checks, and (iii) are particularly aware of how tyre pressure can affect range, road grip, and tyre longevity. Examples of comments include “I have a reading available on my dashboard”; “Sunday is car check day!”; and “Knowing the importance of increased drag from under-inflated tyres on reducing EV range”.  For one respondent, a known slow leak keeps them on their toes and checking daily, while a monthly checker has “been surprised by how they often need inflating a little depending on the weather”. Several are conscious of the fact that “there is no spare tyre in the car” and this fear drives monthly checks.  For others, “memory” is sparked and “whim” moments are enough to keep up the monthly checks.

It’s good to know Flip the Fleet is helping up the pressure ante for some of you! “I read your discussion article that pointed to tyre pressure being an important factor in optimising the performance of an EV. I have found that in 1 month the pressure drops by 3-4 PSI, so I top up the pressure monthly”.  This person will have been responding to our small survey of Dunedin EV tyre pressures that was conducted during a community experiment to test the effects of load on efficiency (https://flipthefleet.org/2017/many-us-inflated-tyres/).

Drivers who checked tyres just “a few times a year” and “once a year” relied more on random thoughts and on chance times becoming available to check their tyres. Many are more likely to check tyres before going on a long trip. Additional indicators that lead to pump-up action include “visible squish” of the tyres, a “go by feel and decide from there” approach, or a “change in season temperatures”.

Two owners had filled their tyres “with nitrogen which holds the pressure better than air”.  This may well be true but we don’t know of any peer-reviewed, scientific evidence to suggest a benefit in doing so.

“Never” responders mostly relied on their service providers or TPMS to ensure tyre pressure remained adequate. One even managed to merge the two! “There is a flat tyre indicator – I do it when it tells me – the car is “the mechanic” in this case”.

Do EV owners check their tyres more than ICV owners?

Frequency of tyre checking hadn’t changed since switching from a conventional combustion vehicle (ICV) to an EV for 60% of participants (Figure 2).   However, more than three times of the remainder increased the frequency of checking tyres compared to those that check their EV’s tyres less frequently than they used to when they owned an ICV.  Amongst the ‘Other’ responses (3%), some hadn’t owned their EV long enough to be sure: “Only had car over 1 month. Not checked tyre pressure yet”.

Figure.2 Changes in frequency of tyre checks for electric vehicles compared to Internal Combustion Vehicles (ICVs).  Percentages are based on 346 choices to Question C, July 2018.

 

Comments suggest that many EV owners apply the “same principles as any car”, although some admit they are consistently “still slack” and others noted there were “more reminders visiting petrol stations and seeing the air filling stations” which made it easier to remember to check air pressure. Some check their tyres “about the same, though [I] recognise that tyre pressure has a greater bearing on efficiency”. This suggests that some owners lack motivation rather than education to follow best practice.

Many EV owners place considerable trust in the onboard instruments that warn them when they need to inflate the tyres. These Tyre Pressure Monitoring Systems (TPMS) make frequency irrelevant: “It is done as required by the car” because the instruments warn when additional air is required. Others said: “Yes, I only probably checked my tyre pressure twice a year, if that. I only did it if I thought the tyres looked a bit down. Leaf Spy has changed all that. It is so easy now because of the prompt if the tyres go below my set pressure”; “Yes. It is the first time I have had a car with TPMS”; “the TPMS changes my tyre management “from a casual look to actual gauging”; and “Now there is no need to check, as car should indicate”.

Range anxiety and a wish to reduce wear and tear motivate some EV owners to increase their frequency of checking tyres: “I probably check it more because I know we would get more range on properly inflated tyres”; “Yes. I have less mileage with my battery range and I like to maximise it. I was less inclined to keep my tyre pressure checked with petrol vehicle I guess I didn’t think about so much!”; and to “reduce wear and tear”.

Range has, however, also featured as a reason for checking tyre pressure less often in EVs: “Yes, it got worse – with our ICE, at least, I checked before road trips. Now we’re really bad...”.  Many owners transfer most of their local travel to an EV and use their second car, an ICV, for the longer trips (https://flipthefleet.org/2018/1-click-survey-20/). As some are far less worried about the effect of tyre pressure on these shorter trips, the EV tyres tend to be neglected: “Yes, haven’t had to check yet and won’t be able to do any long trips due to the range of the car”.

Visits to petrol stations to refuel causes some owners to check their EV’s tyres more, but others less so: “With the Prius I’d always intend to do it while getting petrol and then run out of time. Now as it’s the only thing I have to use the petrol station for I’m actually better about doing it”; “I do it less often on my EV. Tyre pressure on garage forecourts are for paying customers. I don’t pay for petrol”; and “I check much less as now need to make dedicated trip to petrol station”

New EV owners showed a similar mixed response, with one checking “Less as I have more confidence in a newer car”, while another’s checks were “much more frequent, especially as the car is less than a year old”.

“How do you decide what pressure to use?”

What were your thoughts on the ideal tyre pressure? Most tend to agree with following the manufacturer guidelines: “Nissan states 36 psi and they know best since they designed it – why risk sliding in slippery conditions for the gain of a couple of kms?”. The door panel and “owner’s manual” were both ports of call for finding tyre pressure information. Taking into account opinions around tyre pressure and driving efficiency, some participants still couldn’t be swayed: “Door sticker 250/2.5 (35psi). Aware of lots of debate but decided to stick with manufacturers recommendation”; “Manufacturers specs. I prefer a slightly softer ride being in Christchurch with our munted roads. It’s kinder on me and my suspension”.

Several EV owners use the manufacturer’s recommendations as a starting point, but then pump the tyres anywhere between 1 and 5 psi higher: “I go by the book and add a couple of psi. Harder ride but lower rolling resistance and less tire wear. I usually set it to about 40psi in summer”; “rule of thumb is 2 psi above the recommended values. NZ’s coarse-chip roads require a higher pressure”; “5 psi above recommended to give time between refills and to increase efficiency”.

A handful of owners have decided to max out, going with “maximum pressure written on tyre (44Psi)”. Beware a burst! Others have determined their own ‘max’ through trial and error to find their efficiency-safety sweet spot: “Always run around 45psi. Max I can go without causing it to be slippery in the wet”.

Online research helps many owners to decide what pressure to use. Participants look up online manuals, consult EV blogs, interact with Facebook forums, Google for answers and delve into the depths of YouTube: “I watched a YouTube which showed the way to work out what pressure to use”; “Web searched. Included weight factor. Picked 42-45. Noticeably better efficiency in summer”; “I forget so ask Facebook”.

Trial and error, habitual inflation levels, implementing in-person pressure advice, and mixed method approaches rounded out responses. Some found clarity in consulting various information sources: “Manufacturer’s recommendation, adjusted for Internet wisdom & wear observations”; “Some combination of internet opinion moderated by what I think is safe”; “Manufacturer recommendation and experience combined”; “Manufacturer plus NZ EV Facebook discussion”, while others encountered uncertainty: “Advice, BUT EV mechanics advise 40 psi and tyre mechanics advise 32-34 psi”; “I will usually add a couple pf Psi though knowing that it drops with time – also a US blog I read had people pumping them way over (up to 42 psi) to get improved efficiency (reduced rolling resistance). I would like to know if this is safe”.

Your choice of tyres

Just under half (46%) of responders knew which specific brand of tyres they had on their EV (155 of 336 responses, Figure 3). For those that did not know the brand, 7% of all responders mentioned “eco” or “low rolling resistance” as a key tyre feature, while another 22% stated they didn’t know because they were still using the original or factory-fitted tyres that came with the EV at purchase. The remaining 24% were unsure of the brand of tyres on their EV, and did not provide any further information.

 

Figure.3 Types of tyres fitted to electric vehicles in New Zealand.  The percentages are calculated from 336 responses to Question D, July 2018.

 

The presence of original tyres among the fleet was highlighted in the final survey question about the deciding factor when choosing a tyre brand (Figure 4). Most participants stated that they hadn’t had to change tyres yet (69%).  Amongst the remaining 101 responses, while those that had needed to replace tyres were driven by performance, recommendations of the manufacturer, and to a lesser extent the cost or perceived value (Figure 4).  ‘Other’ reasons for choosing a certain brand included loyalty to a favoured brand: “Have always run Bridgestone tyres on all my cars”; “Default to existing status quo”, while some just wanted tyres that did the job: “I have no preference for tyres, except I prefer unpunctured ones…”. The remaining Other responses included “Not applicable”, or leaned towards the decision being an externalised one: “I did not choose”; “I have not selected it”; “previous owner”.

Amongst the half (46%) of you who knew the brand of tyre currently on your EV, most had Bridgestone (stated in 90 responses) tyres, with Dunlop (19 responses), Goodyear (15 responses) and Michelin (13 responses) being less common. The remaining 12% of known brands included Haida (1), Kumho (3), Firestone (1), GT (1), Nitto (1), Nexen (1), Toyo (2), Continental Contisport (1), HiFly (1), Yokohama (3), and Sunfull (1).

Many respondents expressed little interest in the type of tyre they run, or were unable to check at the time of the survey: “Round ones (came with car too lazy to check)”; “The ones that came with it (it’s raining, sorry!)”; “Can’t respond – away from home”; “Factory 2011 tyres from Japan. No idea what they are. They pass WOF, who cares”.

As 69% of participants are still on their original tyres, many have not yet had to confront the choice of what to replace them with. e.g. “UK fitted, never looked”; “Manufacturers recommended – haven’t changed tyres yet from new – 40 000kms and counting.  Some have replaced half of the original tyres or are contemplating a tyre change soon: “Original Nissan Leaf 2016 on the back, energy efficient Goodyear Assurance front”; “We just put 2 Sunfull tyres on the front recently”; “Came with Dunlop Enasave EC300. But likely to change to Bridgestone Ecopia soon”.

Even if exact brand wasn’t known, 7% of participants showed umbrella knowledge of desirable tyre properties, giving statements like: “some sort of eco tyres or better”. “Low rolling resistance” also featured several times, with one survey responder planning to “change to all low [rolling] resistance at next renewal”. So even if the brand evaded people’s memories, they picked up on the efficiency, and environmentally conscious aspects of their tyres.

For the remaining 24% who were unsure of the brand of tyres on their EV, feedback didn’t extend far beyond “good ones”, “standard” ones, and “Black ones, inflatable, made of rubber”. Interesting enough, 80% of those responding with Unsure to the tyre brand question checked their own tyres ‘A few times a year’ or less often.

Figure 4. Reasons governing the choice of tyres fitted to New Zealand electric vehicles. Percentages are based on 101 categorisations of responses to open Question E after exclusion of 228 respondents who were still using the tyres that came with the EV at purchase, July 2018.

 

Factors most affecting new tyre choice included perceived value for money: “Value (mileage vs price)”; “Price. Some eco tires OTT with pricing”; “I never buy the cheapest ones”, along with tyre performance attributes: “Balance between grip and low rolling resistance”; “Durability and quiet tread design”, and whatever was recommended by those in the know: “Mechanic said they were as good as Ecopia for half the price”; “EV forum recommendations”; “International reviews”. With so few of you having to make these decisions to date, it will be interesting to see if one of the above factors begins to edge away from the others in the future.

Some EV owners that are still running on the original tyres are already thinking ahead and forecasted their preferred tyre options in their responses – that’s great!  When it comes time to replace, these participants will “opt for “fuel-saver” tyres, since I have found them to be extremely effective on my petrol car”; “get good quality tyres. I never bothered with my old petrol car because it was on its last legs so I just got cheap tyres”, and base decisions upon “lowest rolling resistance that gives the safest ride”. One participant is very well prepared for their pending replacement: “Have some eco tyres to try next – Hankook Nanotech 3 which I scored cheap off Trademe. Same size as current tyres. Will also fit on lighter rims though”.

Some owners plan to stick to the same tyre out of habit, trust, or brand loyalty: “Have always run Bridgestone tyres on all my cars”; “I wanted original tyres as I assumed they might be designed to maximise efficiency”; “likely to keep with brand/type as at 58,000 km they still have good tread”.

Others wanted to mix it up a bit now that their vehicle purpose and priorities had changed: “Next tyres won’t consider rolling resistance since range is not a consideration. Instead I will go for safety, longevity and quiet”; “According to MacFarlane’s Tyre Centre, snow tyres are hard to get and more expensive, so they fitted low-rolling resistance tyres instead (Goodyear Assurance TripleMax 205/55 R16). They predict a noticeable rise in energy efficiency. It is very noticeable that the car is much quieter on the road – there is way less wheel rumble”.

We’ve got to say, this comment kind of made our day: “New tyres were already on the car when bought, but I got them aligned just in case not done already”. Now that’s attention to detail!

 

Discussion and conclusions

Why is tyre pressure important?

Government, industry, online, and academic resources all highlight the importance of keeping tyres pumped and primed to increase maximum range, save on fuel, and preserve tread for both ICVs and EVs (Table 1).  For example, one commentator stated: “Underinflated tires decrease fuel economy, shorten tread life, have less lateral traction and longer stopping distances, are prone to stress damage, and are more vulnerable to flat tires – all of which increase the risk of vehicle accidents/rollovers.”¹  The studies vary considerably in their predictions of the size of loss in efficiency from low tyre pressure – in one study a 17% increase in fuel consumption is predicted from extremely underinflated tyres.  Increased load increases the penalty on efficiency.

It is also important to keep the tyres well-aligned and to rotate the tyre positions to even out wear.

Having the right tyre pressure is also important for your safety because braking distances are extended if the tyres are flat, especially in wet weather.

 

 

Table 1: Reasons for maintaining correctly inflated and well-aligned tyres.

Sources of this information are listed in the reference section at the end of this report.

 

Oduro et al. note the importance of keeping tyre pressure exactly at or near to vehicle manufacturer recommendations: “For passenger vehicles and light trucks, the tyres should be inflated to what the vehicle manufacturer recommends, which is usually located on a decal just inside the driver’s door, or in the vehicle owner’s handbook. Tyres should not be inflated to the pressure on the sidewall; this is the maximum pressure, rather than the recommended pressure”².  This is recommended because both over inflation and under inflation distort the wheel’s shape – affecting fuel efficiency, handling, and resulting in uneven tread wear as shown in the following diagram:

Correct inflation promotes efficient and safe motoring in all vehicle types, but it is particularly important for EVs because it allows you to achieve your maximum range and overcome “range anxiety” (Table 1).

Justin Edgington, Training and Business Development Manager for Tyreline, kindly shared the below graphic with us. It shows the effect of low tyre pressure on braking distance, fuel efficiency and tyre wear and tear by comparing tyres pumped to 35 psi with those progressively underinflated (32, 28 and 25 psi)³. Of interest is the headline “You can’t tell by looking”, which may speak to those who stated they look for “visible squish” as a cue to pump up your tyres.

 

 

Justin Edgington also commented on the equal risks associated with tyre over inflation: “It is a known fact that over inflated tyres are more prone to damage, punctures and offer less grip in all conditions. Tyres that are already overinflated increase in pressure when in use to way beyond the manufacturers pressure which is not safe”. Bill Prebble, Head of Technical and Product at Goodyear Dunlop Tyres NZ,  also cautions people using tyre pressures above 40 psi, which some of you stated was your current efficiency optimisation tactic: “at higher tyre pressures, the enveloping power of the tread and belt package is reduced, making tyres more vulnerable to damage by impact and more liable to punctures. Additionally, because high tyre pressures alter the steering response and lateral grip curves, drivers may find tyre performance less predictable when higher grip levels are called for, such as in evasive or emergency situations”.

In fact, Justin Edgington quite rightly pointed out that maintaining tyre pressure within the manufacturer’s guidelines is a legal requirement in New Zealand:“NZ roads laws say that the tyres must be inflated as per the manufacturers (vehicle) recommendation. We are aware that most NZ motorists are unaware of this law”.

 

What about tyre rotation?

Rotating tyres from front to back or side to side is another aspect of tyre care that can prolong their safe driveable life (see Table 1). Bill Prebble and Justin Edgington both agree that although “technically there is no essential reason to rotate if all tyres are wearing evenly”, one might consider doing as part of an economically viable tyre maintenance plan. Bill notes that: “If all tyres are wearing uniformly, then the decision to rotate or not is often decided based on whether the consumer wants to replace tyres in pairs or full sets of four, so the decision is often generated by economics / personal affordability”.

According to Justin, tyre “rotations should be carried out whenever an abnormal pattern develops on the tyres – conditions such as saw tooth wear and heel and toe wear along with feathering or scaling all indicate it’s time to rotate. Sloped wear and other visible signs can show the drivers that attention is needed. On some vehicles you can even hear an acoustic hum and in extreme cases a vibration can develop if a rotation is needed”. Bill adds that “while tyre rotation may “even out” some of the irregular wear, it is important to understand and rectify the root cause, and thereby extend the mileage potential of future replacement tyres”.

So how do we know when the time is right for rotating the tyres? A problem Justin Edgington has identified is “that our industry simply applies an arbitrary time or mileage (typically 10,000 kms) whereas in fact it depends on the type of vehicle, vehicle settings and geometry, power, drivetrain, use, power and individual driving style, all of which differ for everyone.  Therefore, it is foolish to suggest a timescale when irreparable damage can be done way before the rotation becomes due”. He uses “New Zealand’s most popular vehicle”, the Ford Ranger as the example, stating: “they generally need a rotation in as little as 3000-5000kms depending on the use and geography”. However, “if regular rotations are undertaken, huge increases in potential tyre mileage can be achieved”.  Given that many other car elements have rapidly progressed yet the tyre recommendations have not changed it’s time for some education and training programmes to update people’s practices and recommendations.

Are we taking technology for granted?

Neglect of tyres may be part of a much bigger problem of people just taking modern technology for granted.  While modern cars of all sorts require much less maintenance than older cars, an EV with its reduced working parts and highly complex electronic monitoring systems may be encouraging a more lax view on (tyre) maintenance displayed by Flip the Fleet survey responders.

Certainly, the survey showed that many owners are pretty oblivious about their tyres.  When asked what sort of tyres they used or preferred, many couldn’t say. Others answered “round ones”, “black ones” and “ones without a puncture”.  Some replied “who cares” or admitted that “pure laziness” prevented them from checking their tyres often enough.  But smarter owners realised the importance of the tyres for vehicle efficiency and targeted low rolling resistance brands.

As for those using their TPMS as the ‘be all and end all’ for receiving alerts, Justin Edgington cautions against sole reliance on this technology for maintaining optimum tyre pressure. In line with Bill Prebble’s advice, Justin recommends even with TPMS to check tyres monthly. “TPMS systems are not infallible either so to keep safe, check tyres regularly”.

Are many EVs driven on under-inflated tyres?

According to Bill Prebble, “while tyre maintenance on internal combustion vehicles is important, the maintenance and selection of tyres on EV’s is critical to the safe and efficient performance of the vehicle”.   We shared results from this 1-Click survey question with Bill, who suggested that “the [Flip the Fleet] respondents are better [at checking their tyres] than the average New Zealander by far”.

This is encouraging and it fits with the results in Figure 2 that show around a third of EV owners now check tyres more often!  But there is still quite a way to go before our tyre care is up to scratch. Best practice is to check and adjust tyre pressure every month, and according to our 1-Click survey, only a third of EV owners currently meet this recommendation.

There are few studies that report the average levels of inflation on cars in service in New Zealand.  However, tyre pressure is known to gradually decrease at around 1 to 2 psi per month if left unattended (https://www.energywise.govt.nz/on-the-road/tyre-pressure/).  Our survey suggests that around two thirds of owners check their tyres no more often than once every six months or even less.  Some of the more aware owners inflate their tyres slightly above recommended levels when they do check, so we do not expect that the full two thirds of tyres will be underinflated, but many will be.  A recent but small survey of Dunedin EV owners confirms this concern – around half (54%) of the tyres on 19 Leafs that took part in Flip the Fleet’s efficiency experiment on 25 November were inflated below the recommended ‘cold tyre’ pressure of 36 psi (https://flipthefleet.org/2017/many-us-inflated-tyres/).  One of those tyres had a pressure of 25 psi, around 30% less than recommended.  There is a need for a much larger and systematic study of tyre pressures used by EV owners before the prevalence of under-inflated tyres can be better quantified.  Bill Prebble reports that the last systematic studies of tyre pressures in New Zealand were conducted in the early 1990s and so are unlikely to still apply.  In the meantime our preliminary survey suggests real cause for concern and highlights the value of more educational campaigns to improve owner practices.  The material provided by EECA’s ‘Energywise’ website, and other websites cited in the reference list below  is excellent, but clearly it is not getting through to many vehicle owners.

Infrequent checking of tyres may be less about participant knowledge of tyre pressure benefits and more about mustering the motivation to check: “The Dunedin EV group checked tyre pressures at the start of one of our community experiments and found a lot were way lower than recommended – but even with that wake-up call (last November) I haven’t increased my checking frequency”.  There is a clear need to raise awareness and encourage routine and habitual checking as a normal part of EV maintenance.

Overall then, participants commonly seek pressures between 35 and 45 psi. Industry advice directs EV owners to stick to recommended tyre pressure or at most, go 2 psi above this amount, but some greatly exceed these guidelines. We strongly recommend that this practice stops.

Many New Zealanders are still coasting along on their original EV tyres.  The kilometres travelled in New Zealand will soon stack up and the earliest model Leafs (2011) are still being imported, with increasing miles travelled and their original tyres fitted.  Overall, responses to our questions highlight just how young our EV fleet is.  Looming large scale tyre turnover is something we should all be aware of and begin preparing for.  It also means now is a great time for Flip the Fleet and others to get some useful tyre information out and about! We’ve made a start in the recommendations section below.

Summary and recommendations:

Tyre pressure checks and adjustments currently aren’t high enough on our priority list, with many leaving it up to memory or whim, tyre misshape, a sub-par driving experience, or their next service check to trigger action.  Our survey suggests that many EV owners have under-inflated tyres.  We urge you to follow the recommendations in Table 2 – your car, tyres, wallet and environment will thank you for it!

A national educational campaign including guidelines for buying new tyres and tips for taking care of them is important for all makes of car, but particularly valuable for owners of the smaller and earlier EV models where efficiency and range maximisation are sometimes more important than in their ICV counterparts.  Tyres are expensive, environmentally toxic to make, run (they give off minute fragments as they wear) and dispose of, so there are good community reasons for making them last as long as possible.

 

 

Your comments in detail:

Below is a lightly edited and re-arranged selection of many of the comments received.

 

What determines your frequency of checking tyre pressures? (Question A)

Simple: when the tyre looks flat!

“When the tyres look low, or feel slightly underinflated x53 similar responses” • “change in tyres” • “When I feel they need pumping up” • “Does it look soft?” • “If tyres look and feel right” • “The feel of the tyre” • “I always worry that 1 or more looks a bit soft” • “Observation” • “visible squish”

My EV lets me know

“I have a continuous reading available on my dashboard/TPMS/LeafSpy” x9 similar responses • “km/KWh drops below 7.3” • “Automatic warning message on dashboard x13 similar responses” • “The car tells me that they are low so I don’t need to check x6 similar responses”

A sub-par driving experience

“Fuel economy and vehicle handling” • “efficiency of drive” x4 similar responses • “Sluggish feeling while driving” • “Feel of ride” • “I can feel the drive soften when the tyres are less than full” • “Vehicle handling feels off” • “How it drives” • “Feels heavy” • “If range is low” x3 similar responses • “if I notice steering/ride issues” • “Hmm. if I suspect they’re a bit flat (feel it when driving)” • “Reducing efficiency, noise, handling or range changes” • “ride and cornering behaviour changes”

It’s part of the routine

“Routine/Habit x6 similar responses” • “Monthly x9 similar responses” • “Call at tyre shop when shopping” • “Sunday is car check day!” • “Monday chores” • “I check out of habit. Every Saturday after I’ve washed the Leaf. Rain and shine” • “Program it on my car screen (leaf)” • “Once in fortnight” • “Part of regular checks x4 similar responses” • “ A reminder in my diary, and any time I think they might be under inflated” • “Monthly checks are easier and allows me to gauge how the tyres keep their pressure. If pressures are not stable, then such frequent checks will soon show up problems with tyres” • “Checklist” • “periodic check on pressure” • “time since last done x1 similar response” • “A little less than monthly” • “ Quarterly check regardless of condition” • “Bi monthly x3 similar responses” • “normally checking tyres even on ICE cars very rarely have to adjust the pressures” • “I try to check them monthly but it usually ends up being less frequently!” • “Daily use visual inspections” • “just a routine and have a compressor at home” • “triggered by a routine service” • “Reminders” • “mean to check weekly but usually forget; current tyres hold their pressure well so monthly seems okay” • “On a set schedule” • “just seems a sensible frequency” • “Annual maintenance” • “Self-determined schedule”

The same reason I check(ed) my ICE tyres

“as per our previous ICE car” • “I do it quarterly as I have always done when I had an ICE car. I don’t do a big mileage. I get wheel balancing done once a year unless I feel the need for it sooner” • “I check my tyres on my ICE car too, monthly, for the reason it needs less petrol”

Longer trips trigger tyre checks

“when I’m preparing for a longer distance trip” x28 similar responses • “Amount of travel” • “With our ICE it’s usually before a big trip, e.g, holiday” • “We check before long trips, but, in our Leaf we don’t do long trips, so doesn’t apply” • “Journeys outside Christchurch”

Owner knowledge and past experiences

“Habit from learning on poor quality cross ply tyres, cheap pressed steel wheels that slow leak, seasonal pressure variation due to temperature” • “Knowing the importance of increased drag from under-inflated tyres on reducing EV range” x5 similar responses • “My knowledge of how quickly they deflate” • “Tyre pressure drops about 1 to 2psi in a month so checking more frequently is not needed” • “To avoid detrimental performance without excessive testing. Have own digital gauge and hand pump” • “been in transport for 40 years and that’s one thing that you check frequently” • “Safety and increased mileage efficiency (petrol and electrical)” • “Experience” x3 similar responses • “Kind of discipline” • “Past variance, not hard to predict how quickly the pressure will change if you know how quickly it has been changing previously” • “Curiosity. Last time I was curious I discovered a rear tyre deflated to 19 psi…a slow leak from a nail puncture. I have since replaced that tyre” • “When I think it needs it” • “Our Kumho Ecowing tires have a low roll-resistance, and I had them filled with Nitrogen, which further improves the smoothness as well as holds the tire pressure much better” x1 similar response • “I read your discussion article that pointed to tyre pressure being an important factor in optimising the performance of an EV. I have found that in 1 month the pressure drops by 3-4 PSI, so I top up the pressure monthly” • “When I need to change pressures – or suspect a leak” • “I think that once a month is sufficient for the distance I drive” • “Whether or not I suspect the pressures have dropped” • “I think there may be a problem” • “If I suspect attire may be low” • “When my husband checks his he checks mine. Whenever he thinks they need it” • “want to keep pressure up” • “Since the last time new tyres were fitted on my Leaf I’ve had a slow leak in the right-rear tyre. It loses 1 pound / day, so I top it up once or twice / week” • “The Dunedin EV group checked tyre pressures at the start of one of our community experiments and found a lot were way lower than recommended – but even with that wake-up call (last November) I haven’t increased my checking frequency”

If/when I visit a petrol station, wash the car, or when the car gets serviced

“booked in for new tyres this coming Friday” • “Car wash” x2 similar responses • “I always check when we visit a service station for trailer hire! Other than that, I need to be better at checking” • “Ease of access to the inflating gear” • “When I’m in the petrol station filling my PHEV with petrol” x2 similar responses • “When for some strange reason I have to go to a petrol station” x1 similar response • “Gas station gauges can be massively out of calibration” • “When the vehicles gets serviced” x3 similar responses • “I don’t worry about it. My mechanic checks it” • “at yearly WOF” • “Suggested by the tyre people I go to” x1 similar response • “Proximity to a service station where I can use the free air” x2 similar responses • “petrol station withdrawal” x5 similar responses • “every 6 months, when I get a warrant .. ” • “failure to get a WOF because of worn tyres” • “Fill LPG at petrol station every week for the shop and take the opportunity of them providing the service” • “The only place to put air in my tyres is at a petrol station and I don’t like going there and I don’t feel comfortable just going to put air in” • “Convenience e.g. spare time near service station” • “The equipment to check tyre pressure” • “whether I feel like a service station pie for lunch”

When I remember, or if I can be bothered, and only if I have the time

“When I remember/think of it” x59 similar responses • “When I have time/it’s convenient” x14 similar responses • “I intend to do it weekly, but it may slip to two-weekly” • “It’s simple. I never need to take the car to a petrol station or do any other maintenance so I forget!!  It’s a worry. I’m trying to kick the tyres more often” • “When the work team remember to do this and reminders from Managers” • “Feels about that time again” x4 similar responses • “Random” x7 similar responses • “Laziness” x3 similar responses • “Just a mental reminder to check in a few weeks’ time” • “Just luck” • “whichever way the wind blows” • “Modern cars and tyres seem to need it a lot less” • “Mainly just getting around to it” • “I suddenly decide I haven’t checked for a while. Better do it!” • “Whenever I remember that I haven’t checked the tyres for a while. Then I think about it for another month… and then hopefully check it” • “I do this occasionally” • “When I have the compressor running in the workshop” • “Opportunity or necessity” • “Knowing where the gauge is” • “Whim” x2 similar responses • “Organisational skills – or lack thereof” • “I have no system” • “often don’t think about it”

Weather pending

“I’ve been surprised by how they often need inflating a little depending on the weather” • “If it’s crappy weather I check the pressures” • “when the weather turns nasty and I have to drive” • “When the weather gets frosty” • “Change in season/temperature” x6 similar responses.

Fear of a flat or bare tyre

“There is no spare tyre in the car” • “The fear of having to replace tyres too soon” • “sensitive to the lack of a spare”

When it’s Flip the Fleet upload time!

“I check the efficiency meter, if it’s low then that’s usually a sign the tyre pressure is low. So I do this monthly as part of the Flip the Fleet data upload” • “Monthly maintenance coinciding with Flip the Fleet data upload – I charge the 12V batteries as well as they are not maintained adequately by the cars system” • “seems to be a good interval and checking FTF data encourages to check tyre pressure too”

Other

“My e-bike gets hard to push so I check the bike and the car” • “I ride a bicycle to work, my wife commutes with the EV.  If anyone has ridden a bicycle with low tyre pressure you can really notice the difference and you work much harder… this is the same with your car is working harder with low tyre pressure” • “Enduring pressure stays up” • “I probably should routinely check them more often” • “When my partner does it as I have never done it before” • “they don’t change much” • “I just don’t think about it” • “I haven’t worked out how to check them with LeafSpy yet” • “to sell it, so haven” • “Just think it’s something I need to do.  Not sure why” • “Being only a recent Leaf owner, decisions to change tyre pressure” • “I am not overly concerned”

 

How do you decide what pressure to use? (Question B)

I go with the recommendations/specifications

“I run to the top end of recommendations” x3 similar responses • “Use recommended/specified pressure” x72 similar responses • “Sticker on driver’s door pillar” x57 similar responses • “maximum pressure written on tyre (44Psi)” • “I do it to a level I was told from where I bought my car from” • “As per what’s written on the tyre” x11 similar responses • “On the wear pattern, factory listed pressure is an indication, but depends on brand tyre, and driving style” • “maximum recommended pressure of 44 PSI … for safety” • “what is recommended by tyre supplier” • “Read manual” x37 similar responses • “Go by the manufacturer’s handbook in relation to the tyre manufacturer” • “Door sticker 250/2.5 (35psi) Aware of lots of debate but decided to stick with manufacturers recommendation” • “As recommended by Renault” • “Online manual” • “Manufacturers or tyre suppliers recommendation. Write front and back pressures inside the fuel cap cover” • “The car tells me that too” • “Advice from my mechanic was to stick to the 36 psi for the tyres I have on. It seems to match the manual default pressure” • “The recommended pressure is 36 psi. I use a foot pump with a gauge attached and have separate, pen-size gauge. When I disengage the connecter to the pump, some air usually hisses out so I err on the side of adding a little extra air. I’ve also read that some other owners recommend 38 psi, so I don’t think this does any harm” • “I check the maximum tyre pressure rating, and knock a bit off” • “Written on the vehicle reg plate”

I go above the recommendations/specifications

“5 psi above recommended to give time between refills and to increase efficiency” • “Manufacturer’s figure + a bit more” • “The recommended pressure plus a bit but careful not to exceed the maximum allowable tyre pressure” x1 similar response • “2psi over recommendation” x8 similar responses • “sometimes run them slightly higher” • “manufactures recommendation plus 1. Do not rely on car equipped auto pressure even via Leaf Spy” • “Manufacturer’s recommendation plus a bit, load expected etc. Safer if higher although that compromises comfort” • “Add 10% to manufacturers recommendation” • “Handbook + 3psi (with good tyres)” • “A bit more than the recommended pressure” • “I go by the book and add a couple of psi. harder ride but lower rolling resistance and less tire wear. I usually set it to about 40psi in summer” • “A bit higher than the max recommended but less than 42psi” • “Factory spec + 5psi or whatever is still comfortable” • “Pressure noted on door pillar, plus a little extra for economy” • “Take it to just above the recommended but so far the losses have been nil” • “Manual plus a little bit” • “Go a few psi above recommended. 40psi” • “I choose firm (a little above recommended pressure) as have not noticed either excessive wear or traction loss” • “Recommended pressure + 4 psi” x1 similar response • “Sticker on the door frame tells me. I usually add 0.1bar” • “I go a bit above recommended pressure for lowest rolling resistance” • “Always run around 45psi. Max I can go without causing it to be slippery in the wet”

I do online research

“Online/web research” x8 similar responses • “Facebook EV owners group discussion” x7 similar responses • “I followed the website recommendation of 42-43 PSI” • “Advice from fellow Leafers re rolling resistance vs safety” • “From forum advice – manufacturer recommended plus about 4psi” • “read it should be about 39” • “Google search on forums to see what others have done and effects” x10 similar responses • “I watched a YouTube which showed the way to work out what pressure to use” • “I google to see what the recommended pressure is for the Nissan” • “I’d probably Google it” • “Search online for Manual

Trial and error/personal preference

“Trial and error” • “Best compromise between range and road grip” x6 similar responses • “Guess” • “I tried a few pressures initially when I got the car but I seem to get the best results at 37kPa” • “Increase until tyre deformation when cornering ceases. Under inflation generates a sensation of wallowing through the corners, body roll plus uncertainty of grip of the road” • “It has been difficult to decide. Bought the Leaf with 28 psi all round and car handled very well with no understeer. Gradually increased the pressure 2psi a month and understeer gradually increased. Now running at 37psi because I need maximum range in winter” • “What I have always used” x2 similar responses • “38 psi is what works for me” • “I go for 38 PSI” • “I like 40psi” • “I use (x)psi because I think it will cause the least rolling resistance” x1 similar response • “I know” • “Depends on what I’m doing – Grass events use different pressures and I use different tyres and pressures for tarmac events and drag races” • “I use 40psi all round” • “Ride comfort” • “Economy” • “Adjust based on wear pattern” • “I set them at 40psi and allow them to drop to 38psi during cold weather”

Advice/word of mouth

“I go by what I was told when I bought the car” • “The bloke tells me what they should be” • “the advice of my mechanic” • “I was told at an EV meet” • “Asked the seller” • “Ask someone” x1 similar response • “Advice, BUT EV mechanics advise 40 psi and tyre mechanics advise 32-34 psi” • “Advice from car vendor” • “Technical advice” • “Garage mechanic told us to pump tyres to 50” • “recommendations from other people” • “what I see others recommend” • “Told me 38-40” • “Advice from other drivers whose expertise I respect” • “I asked my tyre man” • “The previous owner”

I go to the tyre shop

“I go to tyre shop” x3 similar responses • “The tyre guy does this” • “leave it to the technician changing the tyres to inflate them correctly” • “I cheat – go to the mechanics!!!“ • “Pressure details provided by the dealer

I have a mixed-method approach

“Manufacturer’s recommendation, adjusted for Internet wisdom & wear observations” • “Research and trial and error” • “Some combination of internet opinion moderated by what I think is safe” • “40 PSI for less rolling resistance and less tyre wall roll on corners, but below manufacturers” • “Manufacturer recommendation and experience combined” • “Recommended balanced with forums” • “Tyre specification primarily then what others recommend on the forums (about 40psi)” • “Manual, but car will indicate” • “From experience on the type of road I mainly drive on, as advised by mechanic” • “Go by the manufacturer’s handbook in relation to the tyre manufacturer” • “Manufacturer plus NZ EV Facebook discussion”

Other/Unsure

“Guess” • “always go to 32 but I have no idea if this is correct!!” • “Same as last car” • “34psi” • “Haven’t checked pressure yet, but should do it this week” • “Gauge” • “Haven’t done it yet” • “The car does that in the computer” • “No idea. Custom wheels and tires so just put 35 in” • “No idea” x3 similar responses • “I don’t know what they should be. Only bought leaf recently” • “Wireless from each tyre” • “Have it written down”

Compared to your current/previous Internal Combustion Vehicle, has your frequency of checking tyre pressures changed? And if yes, how? (Question C)

I check my tyres more often now

“Yes, much more frequent. Previously I would check every 1 to 3 months” x3 similar responses • “Yes, more often x25 similar responses” • “Have always regularly checked tyre pressure but more conscious of doing so since owning an EV” • “Probably slightly more with EV, would just do internal combustion vehicle when serviced or before a big trip” • “More rigorous about doing it monthly” • “Very rarely checked the tyres on my petrol car and only if they looked flat” • “Yes. Never used to bother” • “I check them more frequently, but I do my ICE as well so it’s all good” • “Yes, about twice as often with the Leaf” • “A bit more regular” • “Yes, slightly more conscious of it” • “Check more often but less concerned about pressures” • “Yes.  More important to maintain good pressure for an EV” • “More careful now” • “yes – increased. With the Prius I’d always intend to do it while getting petrol and then run out of time. Now as it’s the only thing I have to use the petrol station for I’m actually better about doing it” • “Compared to my road cars – lot more frequently” • “a bit more sensitive” • “Yes. Monthly for ICE” • ““Yes, was notorious for not checking tyre air pressure and then getting warnings from mechanics” • “Increased on the Leaf” • “Yes. More often, previously perhaps one every 6 months, or before a long trip”

More often, because of EV technology

“Yes, I didn’t have the on-board measure available so checking was infrequent, say every two to three months” • “from a casual look to actual gauging” • “Yes, I only probably checked my tyre pressure twice a year, if that. I only did it if I thought the tyres looked a bit down. Leaf Spy has changed all that. It is so easy now because of the prompt if the tyres go below my set pressure” • “I do it more often, since my car has a TPMS with a dashboard display” x6 similar responses • “dash warning – car was delivered at half recommended pressure. Just purchased the car so assumed dealer/service had it covered” • “Frequency has increased mainly due to the regular reminders. I have always been aware of the need to keep tyre pressures correct to minimise drag and reduce tyre wear so the reminder is a great way to keep on top of these things”

More often, to maintain range and protect my tyres

“Yes, more frequently to maintain range (efficiency) and wear performance” x10 similar responses • “yes, extra weight” • “Yes. Previously checked about twice a year; and didn’t really consider the tyre pressure a significant factor related to efficiency” • “Yes. I have less mileage with my battery range and I like to maximise it. I was less inclined to keep my tyre pressure checked with petrol vehicle I guess I didn’t think about so much!” • “Yes, more range anxiety” • “Yes, more frequent as aware tire pressure can improve efficiency (more?) in an EV” • “I have a specific issue with one wheel. The others have been fine for months” • “It has changed now that I discovered that slow leak. With my last ICE I would really only check pressure at WOF time or if a tyre looked low. Now with my EV I will check at least once a month”

More often, because I’m a new EV owner

“More often – but this is partially because I’m a new EV owner” • “Yes – much more frequent, especially as the car is less than a year old. Also, I ride a bike and have learnt the difference tyre pressure can make to that experience” • “I check more often now because I am reminded of it to do monthly data uploads. Also, because tyres on the EV seem to lose pressure quicker than my old petrol car”

No change in tyre-checking frequency

“No/No change/Same x201 similar responses” • “No. I always check tyre pressures regularly on bikes, motorbikes and cars. Mainly for safety reasons and to ensure optimal handling” • “Same principles as any car” • “not really – tend to rely on a visual check at home, and then confirm when it appears needed” • “Not really, I was always very tyre pressure aware, I did not want to waste petrol.  I am a little more aware now with an EV” • “Probably the same. But had more reminders visiting petrol stations and seeing the air filling stations” • “Not really, I was aware of the need to keep an eye on it already” • “No. It’s important for both” • “no, same logic, same pressure” • “No – I’d always check before going on a road trip” • “Not really, but maybe. Used to check petrol car before long trips” • “No, should I?” • “No (I use nitrogen for tires)” • “Nope.  I looked at them and thought one was a bit down so took it to the local tyre place, mainly to show off my EV.  Apparently the one I thought was down was ok but another one was definitely down” • “About the same, though I recognise that tyre pressure has a greater bearing on efficiency” • “I do not recall ever personally checking tyre pressure on my previous vehicle in 20 years of ownership” • “I always checked tyre pressures weekly – after riding motorcycles for 15 years before owning a car it’s just second nature as tyre pressures on bikes have to be spot on if you ride them to their potential” • “No, but am aware that tyre pressure can affect battery usage

I check my tyres less often now

“Yes, check tyre pressure less x6 similar responses” • “I may check less often as we don’t use the leaf for long trips” • “compared to my old track mini (80s) a lot less frequently”

Less often, due to less petrol station stops

“Have to make an effort to stop at petrol station” x1 similar response • “Decreased since I visit service stations so much less frequently!” x12 similar responses • “Yes – I do it less – tyre pressure on garage forecourts are for paying customers- I don’t pay for petrol” • “Yes. Because I had a petrol car, I was always at the petrol station and so I’d check it every couple of weeks, and because that car’s tyres always needed topping up. The EVs doesn’t seem to lose pressure like [an ICE]

Less often, because of less longer trips

“Yes, it got worse – with our ICE, at least, I checked before road trips. Now we’re really bad…” • “Yes, haven’t had to check yet and won’t be able to do any long trips due to the range of the car”

Less often, because of EV technology

“Yes, less because I leave it to the car” • “less, due to the automatic sensor” • “Now no need to check, as car should indicate

Less often because I’m a new EV owner

“Less as I have more confidence in a newer car”

Other/NA/Unclear direction of frequency change

“Only had car over 1 month. Not checked tyre pressure yet” • “Yes. It is done as required by the car” • “More aware of importance” • “NA Only had the car a month” • “Not needed yet as have only had EV for 5 months” • “Yes, I used to check my previous petrol driven car fairly regularly as the correct tire pressures were on a metal plate inside the right front door jamb”

What sort of tyres do you have on your EV? (Question D)

Michelin

“Michelin Energy Saver” x3 similar responses • “Michelin low rolling resistance” • “Michelin 195/55 R16” • “Michelin Green Energy Saver 205/55R16” x2 similar responses • “Michelin as fitted at the time of manufacture” x2 similar responses • “Michelin 165/55 16 economy” • “Michelin as for UK Leaf”

Bridgestone

“Bridgestone” x12 similar responses • “Bridgestone Ecopia EP150 205/55 R16” x21 similar responses • “Bridgestone Ecopia EP-300 tyres” • “Bridgestone Ecopia” x51 similar responses • “Performance tyres that came with the optional Nismo leaf 18″ wheels. Bridgestone RE001 from memory” • “Originally had Bridgestone Ecopia E300 on the front, but one of them spontaneously punctured in the side wall” • “The Ecopia low rolling resistant tyres that come with the Leaf. I don’t know if they are originals or replacements done in Japan” • “Bridgestone Potenza re003 245/40/17” • “Bridgestone eco (new version of original)” • “What they came with, Bridgestone Traction and Temp tyres” • “Bridgestone RE002” • “Bridgestone Turanza”

Goodyear

“Original Nissan Leaf 2016 on the back, energy efficient Goodyear Assurance front” • “Goodyear Optilife” x2 similar responses • “Goodyear ‘EfficientGrip 185/65R15 92H” x2 similar responses • “Goodyear Eco” • “Goodyear Assurance TripleMax” x4 similar responses • “Goodyear Efficientgrip 185/65R15 92H” • “Goodyear Assurance Tyremax” • “Goodyear Efficient Grip on the front” • “Goodyear Assurance fuel savers

Dunlop

“Dunlop Enasave EC300 x11 similar responses” • “Nissan Leaf factory fitted Dunlop Enasave” • “Dunlop” • “Came with Dunlop enasave EC300. But likely to change to Bridgestone Ecopia soon” • “Dunlop LM704 (came with the car)” • “Dunlop 215-50 R17 91V x2” • “Dunlop Enasave (factory originals still)” • “Dunlop DSX-2 205/55 R16 91Q (Winter tyres)” • “Dunlop 205/55 A16

Other brands

“Yokahama Ecos” • “Haida” • “Kumho Solus TA31 225/40R18” • “Road Fit SK10 215-50 R17 91W” • “Kumho” x1 similar response • “Firestone – Standard that came with the EV” • “I have Nitto semi slicks on the back” • “Nexen N’blue HD 205/60R16” • “Continental Contisport” • “HiFly HF201 205/55 R16 91V” • “[Yokohama] blue earth” • “[Nissan] e-NV200” • “We just put 2 Sunfull tyres on the front recently” • “[GT] Radial” • “[GT] Radial steel belted” • “ Toyo proxies” • “Hyundai manufacturers tyres for EV” • “Yokohama, I think” • “Kumho Ecowing” • “GT radial low rolling resistance” • “Khumo Wattrun on the Leaf I think” • “Toyo NanoEnergy3 plus”

Original/Factory-fitted/Standard/What the car came with

“tyres that came with car” x38 similar responses • “Factory fitted” x14 similar responses • “Round ones (came with car too lazy to check)” • “Originals/OEM x13 similar responses” • “God knows. The ones that came with the beast” • “Standard i-MiEV tyres” • “Standard, whatever Tesla supplied!” • “Japanese tyres as when purchased. Due for replacement before next WOF” • “The manufacturers” • “Standard tyres I” • “Standard 16″ non-directional” • “17 inch supplied with car” • “Factory 2011 tyres from Japan. No idea what they are. They pass WOF, who cares” • “UK fitted never looked” • “The standard specially designed ones that come with the i3” • “Those recommended for i3 by BMW” • “The standard Nissan Leaf tyres” x3 similar responses • “Manufacturers recommended – haven’t changed tyres yet from new – 40 000kms and counting” • “Would have to check. We’ve had it for two years now” • “Standard”

Low rolling resistance, green/eco, radial

“low rolling resistance tyres x10 similar responses” • “eco somethings” • “Some sort of eco tyres or better” • “green tyres” x1 similar response • “Low profile radial” • “two low resistance tyres and two regular tyres” • “Radial” • “ECO – type”

No idea/Don’t know/Unsure/Other

“Pneumatic” • “EPV1AZ if that helps” • “Don’t know/not sure/unsure/no idea” x34 similar responses • “Haven’t looked at them yet” • “Rubber ones x5” • “Can’t respond – away from home” • “??? x4 similar responses” • “Round ones x6 similar responses” • “Sorry I am on holiday so do not know” • “two original two replacements no idea” • “Nothing special” • “I don’t know, just normal tyres” • “Fat ones.  Sorry, I’m a bit of a girl with cars.  I’m told they are good ones for an EV” • “Econo • “Regular tyres” • “Generic low profile” • “Directional” change to all low resistance at next renewal” • “Lower profile g model tyres as imported” • “30 to 32psi” • “Good ones” • “Black ones, inflatable, made of rubber” • “Something other than Ecopia”

What determined your choice of tyres? (Question E)

Still got the tyres the EV came with…

“Came with the vehicle x182 similar responses” • “Factory” x7 similar responses • “Haven’t had to change them yet so haven’t had to choose” x10 similar responses • “No decision has yet been made – there’s still 6mm of tread all around” • “Was fitted by Nissan Europe” • “Original tyres” x3 similar responses • “As supplied!” x2 similar responses • “Supplied by vehicle manufacturer” • “As purchased” • “Tesla agency decided” • “At this stage, I’m just using the tyres which were on the vehicle when I bought it” • “As supplied new and did replace one with a slightly damaged sidewall” • “Previous owner” • “New tyres were already on the car when bought, and got them aligned just in case not done already” • “those recommended for i3 by BMW”

…but when replacements are needed…

“when they need replacement, I will opt for “fuel-saver” tyres, since I have found them to be extremely effective on my petrol car” • “But when I need to replace, I would like to get good quality tyres. I never bothered with my old petrol car because it was on its last legs so I just got cheap tyres” • “decision will be based on lowest rolling resistance that gives the safest ride” • “When we go to buy new, we’ll look for low-noise and low-rolling resistance tyres. We’ll evaluate factory-recommended options and compare to what’s available aftermarket” • “but I would stay with the most efficient tyres I can find at a reasonable price” • “but will go for low rolling resistance when replacing in due course” x1 • “Have some eco tyres to try next – hankook nanotech 3 which I scored cheap of TradeMe. Same size as current tyres. Will also fit on lighter rims though” • “When they need replacing we will get the best tyres that give us the best range combined with the best safety and longevity” • “I will likely choose different wheels when I change tyres, to the ones I prefer – i.e. best safety.  I had Yokohamas on my last car with asymmetrics” • “but I will look for longevity and low rolling resistance” • “But will replace with a new one the same as it is replacing” • “Will look for economy next time they are due to be replaced” • “Next tires won’t consider rolling resistance since range is not a consideration. Instead I will go for safety, longevity and quiet” • “but I will consult manual and mechanics when need to replace” • “may make a different choice when they need replacement” • “Want relatively low rolling resistance, but also good wet weather performance” • “maximum grip in wet conditions”

I went with recommendations

“advise of supplier” • “Manufacturer recommendation” x10 similar responses • “Usually a recommendation from local tyre guys” • “What was recommended for the car”  x1 similar response • “EV forum recommendations” • “I trust my mechanic” • “recommendations from other EV owners” • “Manual” • “Web compare” • “Next time mechanic said to get Fuel savers” • “suggestion of the technician doing the changing” • “Whatever is recommended when I buy them” • “The ones they sell me” • “International reviews” • “Tyre dealer pointing out the highest efficiency tyres also had the least tread and therefore were not actually a great buy” • “I wanted low rolling resistance tyres to replace the factory ones; This was what the local shop had” • “Advice of my tyre shop. A good tyre for metal roads” • “Mechanic said they were as good as Ecopia for half the price” • “The salesman” • “Will check recommendations on the Facebook groups”

Cost was paramount

“Cost/price” x16 similar responses • “longevity” x1 similar response • “Value (mileage vs price)” • “Price, some eco tires OTT with pricing” • “I never go with the cheapest ones” • “Will probably go mid-price range because of shorter distances travelled from home compared to ICV” • “Price to Quality Ratio. Don’t buy the cheapest, and don’t get the most expensive (unless proven worthwhile) ” • “Historically, price is a deciding factor when replacing tyres” • “After agonising about what tyres to put on the Zoe when it needed new tyres, I just went for some el cheapo” • “Cheap, would look at better ones when replacing next”

The tyres that perform best on the road and will last were the ones for me

“I wanted low rolling resistance to maximise range/efficiency” x10 similar responses • “Fuel efficiency” x6 similar responses • “Good Braking performance” • “(wet) grip performance” x5 similar responses • “Wear” • “Performance” x4 similar responses • “Supposedly more range” • “Best tyre for the type of car” • “Durability and quiet tread design” • “Quietness” x1 similar response • “Noise” • “Safety” x2 similar responses • “Quality” • “Previously had Ecopia and they were crap so went the next model up when I replaced the tyres” • “Suitability” • “My WOF test recently forced complete replacement of the original tyres that came with my 2015 24 kWh Leaf import (now at 38 km). The originals were snow tyres (Dunlop 205/55- 16 Winter Max WM01). Even though only two tyres were below the minimum tread depth, all four had to go unless I continued with the snow tyres all round i.e. a mix of snow and ordinary tyres is not allowed. According to MacFarlane’s Tyre Centre, snow tyres are hard to get and more expensive, so they fitted low-rolling resistance tyres instead (Goodyear Assurance TripleMax 205/55 R16). They predict a noticeable rise in energy efficiency. It is very noticeable that the car is much quieter on the road “there is way less wheel rumble”

I stuck with what works!

“Will replace tyres with similar when required” • “Have always run Bridgestone tyres on all my cars” • “Brand” • “Whatever the EV came with however I will not use re-treads” • “Default to existing status quo” • “likely to keep with brand/type as at 58,000 km they still have good tread” • “OEM” • “OEM fitted” • “Offered by Beaurepairs” • “I wanted original tyres as I assumed they might be designed to maximise efficiency”

NA/Other

“Not applicable yet x4” • “From new…” • “Convenience” • “I have no preference for tyres, except I prefer unpunctured ones…” • “They came stock from the car yard” • “All sorts” • “What I really need is a spare wheel as we’ve had to get the AA out twice” • “Nissan” • “I didn’t choose” x7 similar responses

References

¹ Pearce, J.M., Hanlon, J.T. (2007). “Energy Conservation From Systematic Tire Pressure Regulation”. Energy Policy, 35(4), pp. 2673­2677.

² Oduro, S., Alhassan, T., Owusu-Ansah, P., Andoh, P. (2013). A Mathematical Model for Predicting the Effects of Tyre Pressure on Fuel Consumption. Research Journal of Applied Sciences, Engineering and Technology. 6. 123-129. 10.19026/rjaset.6.4046.

³ Provided by Justin Edgington, Training & Business Development Manager (Group), Tyreline.

⁴ Provided by Bill Prebble, Head of Technical and Product, Goodyear Dunlop Tyres NZ

⁵ EECA. (2018) EECA Energywise: Tyre pressure. Accessed July 2018: https://www.energywise.govt.nz/on-the-road/tyre-pressure/

⁶ Electronic Specifier (2018). How to make the most of your tyres on an electric vehicle. Blog published online 3^rd July 2018. Accessed 19^th July at: https://automotive.electronicspecifier.com/ev/how-to-make-the-most-of-your-tyres-on-an-electric-vehicle

⁷ EECA. (2018). EECA Business: Tyres for cars, vans and utes. Accessed July 2018: https://www.eecabusiness.govt.nz/technologies/vehicles/cars-vans-and-utes/tyres-for-cars-vans-and-utes/

⁸ Schuring, D.J. and Futamura, S. (1990). Rolling loss of pneumatic high-way tire in the eighties. Rubber Chem. Technol., 63(3): 315-367.

⁹ Calwell, C., Ton, M., Gordon, D., Reeder, T., Olson, M., and Foster, S. (2003). California State Fuel Efficient Tire Report: Volume II, California Energy Commission, 600­03­ 001CR. Available: http://www.energy.ca.gov/reports/2003­01­31_600­03­ 001CRVOL2.PDF

¹⁰ Hadrys D, Wegrzyn T, Miros M. (2008). The Influence of various pressures in pneumatic tire on braking process of car with anti-lock braking system. in Transport Problems, 2008.

¹¹ Besselink, I. J. M., Schmeitz, A. J. C., & Pacejka, H. B. (2010). An improved Magic Formula/Swift tyre model that can handle inflation pressure changes. Vehicle System Dynamics, 48(S1), 337-352.

¹² Penant, C. (2005). Michelin: The Challenge of Energy Efficient Tyres. Presentation at the International Energy Association Workshop on Low Rolling Resistance Tyres, Paris 11/2005

¹³ Zervos, H. (2010). Tyre pressure monitoring systems and energy harvesting. Off Grid Energy Independence, accessed 17^th July 2018. https://www.offgridenergyindependence.com/articles/2587/tyre-pressure-monitoring-systems-and-energy-harvesting

¹⁴ Savitski, D., Hoepping, K., Ivanov, V., & Augsburg, K. (2015). Influence of the tire inflation pressure variation on braking efficiency and driving comfort of full electric vehicle with continuous anti-lock braking system. SAE International Journal of Passenger Cars-Mechanical Systems, 8(2015-01-0643), 460-467.

¹⁵ Redrouthu, B.M., Das, S. (2014). Tyre modelling for rolling resistance. Department of Applied Mechanics Division of Vehicle Engineering and Autonomous System Chalmers University of Technology. Masters Thesis 2014:24 ISSN 1652-8557. SE-412 96, Göteborg, Sweden.

 

Additional resources

EECA Energy-wise: Tyre Pressure

Includes a step-by-step video of how to check your tyre pressure

https://www.energywise.govt.nz/on-the-road/tyre-pressure/#Checkingyourtyrepressure

EECA Energy-wise: Tyre Pressure Tool

Calculate the recommended tyre pressure for your specific car

https://www.energywise.govt.nz/tools/tyre-pressure/

TyreSafe UK

Test your tyre knowledge with their 20-question quiz!

https://www.tyresafe.org/

 

Acknowledgements

We would like to express our utmost appreciation for the contributions made by Bill Prebble and Justin Edgington for teir peer review of this 21^st Flip the Fleet 1-Click survey and blog. Your knowledge is amazing and you gave generously of your time.  A hearty thanks to you both!

Any further questions?

Justin Edgington has kindly agreed for you to personally get in touch should you have any further tyre-related questions or queries.

Justin Edgington

TRAINING & BUSINESS DEVELOPMENT MANAGER (GROUP)

Tyreline Distributors Ltd

 

Phone: +64 (7) 843 3552

Mobile: +64 (0) 27 839 7101

Fax: +64 (7) 843 3582

Email: justin@tyreline.co.nz

 

 

 

This report was prepared by:

Hannah Gentle, Henrik Moller, Dima Ivanov and Daniel Myall

23 June 2018