Top Tips for EV Tyres

Heads up!  This is important

Under-inflated tyres

• have less lateral traction and longer stopping distances (by 11 meters when the road is wet)
• decrease fuel economy (by up to 17%)
• shorten tread life (by up to 30%, or 15,000km)
• are prone to stress damage
• and are more likely to puncture

Over-inflated tyres

• make the car harder to control when you have to swerve or do an emergency stop
• are more likely to blow out if you hit a kerb, stone or pothole
• shorten tread life

Tyres lose about 1 pound per square inch (psi) of air pressure each month under normal driving conditions and even more if temperature changes^1,2,3.  So it’s really important that you check your tyre pressure at least every month and when necessary pump them up to the recommended pressure^1-9.  And never deliberately over-inflate them unless you are about to carry a heavy load.  Correct inflation could save your and others’ life and will be good for your power bill, maintenance bill and the planet (manufacture, wear and disposal of tyres is environmentally damaging). The added efficiency could also make the difference between reaching the next rapid charger on a long trip and reduce the time you have to spend charging.  Finally, having correct tyre pressure is a legal requirement, not just an option when you get around to it.  So, let’s do it!

What to do

1. Check your tyre pressure at least once a month, when cold (driven less than 3km) to optimize efficiency, safety and durability^2,3,4
2. Maintain inflation pressure at that shown on the vehicle placard or in the manual^2,3,5
3. If desired or carrying heavier loads, consider going 3 to 4 psi above the car manufacturer’s recommendation, but remain safely below the maximum pressure stated on the tyre^2,5
4. Check wheel alignment! Do it regularly, especially if your car has driven over large potholes or hit roadside kerbs⁶
5. Inspect tyres regularly for uneven wear. If present, rotate tyres to distribute wear across the tyre surface, but also investigate the root cause e.g. wheel misalignment³
6. Always run with a valve cap fitted securely on each wheel⁴

What not to do

1. Tyres should never be inflated above 40 psi. As tyres heat up while you drive, they’ll naturally increase in pressure. Beginning at maximum pressure puts you at major risk of a tyre blow out, and may compromise your car’s ability to swerve or stop in an emergency³
2. Avoid sole reliance upon technology for alerts and warning signs. Some models have an automated Tyre Pressure Monitoring System that flashes a warning symbol on the dashboard when pressure becomes too low. These are intended as a last-minute warning before imminent tyre failure, not as a monitor to make sure your tyres are properly inflated.⁷
3. Avoid strong acceleration during the first 24 hours following a tyre change in order to allow the fitting grease to dry out between the tyre and the rim. This will prevent the tyre from moving in relation to the rim⁵

 

Tyre selection:

1. In general, tyres specified as original equipment for EVs are specifically designed with low rolling resistance for improved driving efficiency. When new tyres are inevitable, attempt to replace like-for-like or select a premium tyre that has “fuel efficiency”, “energy saving” or “low rolling resistance” as a key product feature³
2. Do not be tempted by low cost tyres. These generally have cheaper tread compounds and higher rolling resistance, neither of which are desirable tyre traits³

 

 

“Remember, air is one of the few things still “free” for motorists, so take the opportunity!”

– Bill Prebble, Head of Technical and Product, Goodyear Dunlop Tyres NZ.

 

 

References

These hot tips are based on the following sources:

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

² EECA. (2018) EECA Energywise: Tyre pressure. Accessed July 2018: https://www.energywise.govt.nz/on-the-road/tyre-pressure/

³ Information provided by Bill Prebble, Head of Technical and Product, Goodyear Dunlop Tyres NZ.

⁴ Information provided by Justin Edgington, Training & Business Development Manager (Group), Tyreline.

⁵ 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

⁶ 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/

⁷ Demere, M. (2012). Popular Mechanics: 6 Common Tire Myths Debunked. Accessed July 2018 at: https://www.popularmechanics.com/cars/how-to/a3121/6-common-tire-myths-debunked-10031440/

⁸ 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.

⁹ 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.

 

You can read the (somewhat concerning) results of a recent survey of EV owners practices concerning maintaining tyres at https://flipthefleet.org/2018/optimum-tyre-pressures-and-tyre-types-for-electric-vehicles-one-click-survey-21/. The majority of EV owners are not checking tyre pressures often enough.  A small sample of measurements of EV tyre pressures in November 2017 also confirmed that many EVs are being driven on under-inflated tyres https://flipthefleet.org/2017/many-us-inflated-tyres/.

 

Hannah Gentle & Henrik Moller

30 July 2018