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. The problem may be even worse than these figures suggest because we measured our tyres on a warm morning after they had just been driven to the assembly point for the start of the experiment. Warm tyres have higher pressure than cold ones, and the recommended level of 36 psi is for cold tyres (measured at least 3 hours after being driven). See http://flipthefleet.org/2017/effects-load-eco-stetting-route-efficiency-dunedin-ev-community-experiment/ for a description of the Dunedin experiment.
Of course, our sample size is small, but this preliminary investigation does run up a warning flag that some people compromise efficiency (km/kWh) and even safety by not maintaining their tyres at sufficient pressure. We urge all EV owners to check their tyre pressure regularly (they will gradually deflate in normal running conditions). Perhaps other EV supporter groups could measure a sample of the pressures on the EVs that assemble for one of their events to check whether this preliminary result from Dunedin is a sign of a wider problem. If you do investigate, please post what you discover back here so we can all track the national outcome.
More generally, we would value the opinions of other EV owners about adjustments of tyre pressure for make of tyre (are any deviations recommended) or what they have noticed about the effects of pressure on their EV’s performance. Overseas blogs report that some people inflate their tyres up to and even beyond 40 psi. Do you agree with the manufactures recommendation of 36 psi, and what would be the consequences of over inflation?
27 November 2017