EV owners should stop gloating about how they are reducing vehicle pollution, as opposed to the dinosaurs driving cars with internal combustion engines. A new study from British global testing firm Emissions Analytics, updating a 2020 study, finds that when it comes to small particulate emissions, battery electric vehicles’ emissions are “1,850 times greater” than EVs. The 2020 study found EV particulate emissions (which can be harmful to health when inhaled) 1,000 times greater than conventional cars.
The culprit is the tires on the electric cars. Or “tyres” as the Brits spell them. As the Carbuzz website observed, “Obviously, these silent commuters aren’t spewing anything from their non-existent tailpipes – but their tires are another story.”
The British firm noted that the original study “generated the most feedback of any subject we have tackled so far – feedback that was a mixture of surprise and scepticism….Particularly vocal were the battery electric vehicle (BEV) community sensitive to any suggestion that the added weight of these vehicles might lead to tire wear emissions that might confound the ‘zero emissions’ tag.”
EVs, because of the weight of the batteries and the increased torque of their electric motors, cause greater tire wear than conventional cars, the study notes. Aggressive driving exacerbates the problem. But, says the study, “a gentle BEV driver, with the benefit of regenerative braking, can more than cancel out the tire wear emissions from the additional weight of their vehicle, to achieve lower tie wear than an internal combustion engine vehicle driven badly.”
Carbuzz notes that tire manufacturers are looking at the problem, and Michelin now offers the first “low-carbon” production tire, with reduced rolling resistance, in order to save fuel.
The study points out that tailpipe emissions are airborne while most emissions from tires fall to the ground. Nevertheless, “around 11% of the mass of tire emissions is smaller than 2.5 microns in diameter (defining the common metric for fine particle dust, PM2.5, which can be airborne). Therefore, the airborne tire emissions are more likely to be around 8 mg/km… – this is still more than 400 times higher than tailpipe emissions.”
Tires, which most drivers don’t think much about, are important for owners of EVs. According to Motor Trend magazine, “Tires are an easy to overlook part of a car, in part because they’re so durable and low-maintenance. But despite their willingness to put in years of thankless work, your electric car’s tires are even more important to its overall performance and range than they are to a conventionally powered vehicle.”
Two items are particularly important for EV tires: avoid under-inflation, and buy the right replacement tires. Motor Trend says, “The easiest way to negatively impact your EV’s range is to drive it on underinflated tires—even being low by a few PSI can make a meaningful difference in rolling resistance, and therefore efficiency.”
As for tire replacement, the article says “tires that were originally equipped on your electric car were very likely developed for use on that car. Accordingly, the tire’s characteristics such as noise profile, longevity, grip, and rolling resistance are sometimes optimized to that specific vehicle’s traits.”
–Kennedy Maize
Twitter (kennedymaize)