Every so often, I come across a headline so absurd that I expect the source to be The Onion (or a similar satirical publication). Such was the case recently with “New Study: EVs Create Worse Emissions Than Gas Engines.”¹ MotorBiscuit.com is a relatively new, but apparently serious entry into automotive journalism. In this case, however, the headline is at best a gross misrepresentation of the data—at worst an outright attempt to besmirch electric vehicles (EVs). 

The article cites a recent report from Emissions Analytics, a UK company that (according to their website²) originally formed to study tailpipe emissions, but has expanded to include, among other things, “brake and tire pollution.” Reading the original report from Emissions Analytics reveals a much more nuanced picture. First of all, the headline on the original report is “Gaining traction, losing tread pollution from tire wear now 1,850 times worse than exhaust emissions,” which clarifies that the comparison is actually between engines and tires, not combustion versus EVs. Also, the comparison is specifically of particulate emissions, which are already very low (and getting lower) for gasoline engines. It does not consider tailpipe emissions (unburned hydrocarbons, oxides of nitrogen, CO and CO₂) of which EVs produce none. 

So, any vehicle with tires (gasoline, diesel or electric) generates far more particulate emission from tire wear than from the motor. These particles, especially those with sizes below about 10 microns, are a significant concern, and rightly should be minimized. So, do EV tires actually wear faster than those on conventional vehicles? 

The answer appears to be a function of vehicle weight. Battery EVs tend to be much heavier than a comparably-sized combustion vehicle, due to the weight of the battery pack. Several independent analyses³ conclude that real-world tire wear on EVs is about 20% greater than that of a similar conventional vehicle. So a less sensational headline on the subject might be “EVs Generate 20% More Particulate Emission From Tire Wear,” which is certainly less sensational than the original version. 

Is that the end of the story? Not quite. Recall that Emissions Analytics claims to be interested in pollution from both tire and brake wear. While the tires on EVs wear marginally faster, real-world data also shows the brake pads wear about four times slower. Every modern EV uses some form of regenerative braking, where the motor operates as a generator when the vehicle slows, recharging the battery. The mechanical brakes only operate when it is necessary to slow the vehicle faster than the motor can, such as during panic stops. The result is brakes on EVs are rarely serviced for brake wear. 

A much more fair version of the original headline, therefore, might be “Total Particulate Emissions from EVs on Par With Gasoline Vehicles.”

REFERENCES
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