Wacky World of Rubber: How quickly will EVs catch on?

There's no doubt there's a push in the U.S. toward trying to make electric vehicles one of the main components to what the nation's future mobility landscape will look like. But there's also questions on how quickly the American public will take to EVs. And in the meantime, there's still a lot of testing to be done.

To that end Chris Napier, a senior application development engineer in butyl polymer technology for ExxonMobil Chemical, delivered a plenary address during the recent ITEC In Focus Green Tire Conference, organized by Rubber & Plastics News. His speech topic was right on point with the conference's theme, presenting his company's findings on the "Effect of Tire Inflation Pressure on Electric Vehicle Performance."

But Napier also made a few side observations during his talk. First of all, he took note that the Sheraton Suites Hotel in Cuyahoga Falls, Ohio, where the conference was held, had six parking spots out front set aside for EV charing stations. As far as he could tell, though, nobody had made use of the stations during the two days he had been there.

After hearing this, I of course had to take a look for myself. When I checked, there was indeed a vehicle parked at one of the stations. Lo and behold, however, it wasn't even an electric vehicle, just a standard internal combustion engine car, where the driver apparently wanted a primo parking spot.

As for Napier's talk, he explained that there were some differences between this study and the ones ExxonMobil had done on standard ICE vehicles for years. For example, efficiency in an EV is measured by miles per kilowatt hour, rather than miles per gallon.

For the test, ExxonMobil chose a Chevrolet Bolt, largely because it was one of the few EVs touting a range of more than 200 miles per charge. He was quite surprised that some EVs only promised about 100 miles on a charge, and Napier said General Motors' promise of 240 miles for the Bolt was pretty accurate.

ExxonMobil had to overcome some obstacles in running the tests, even though EVs to this point still run on fairly standard tires. For the test, the materials firm chose one original equipment tire brand and two replacement brands. The listed rolling resistance was the same for all three tires used in the testing, he said.

One logistical issue involved charging of the vehicles. It took six hours for a full charge, and Napier said it had to be done overnight, because charging all three cars at once was too much of a load during the day for the building where the tests were done out of. With other electrical needs, the system couldn't handle charging the vehicles during the day.

In addition, everything runs off the battery in an electric car, with one of the biggest draws on power being the heat and window defroster. Because of that ExxonMobil had to make calculations to determine how much of the draw on the battery was caused by all the other uses, and estimate how much was because of the underinflated tires.

As for the Bolt itself, he said it felt pretty much like a normal car. Everything was pretty much where it was supposed to be, and it was "peppier than I thought." Napier did note, though, that cabin noise seemed to be much more of an issue, and that proper inflation did help with the noise level.

The tests showed that tire underinflation over time caused the range per charge to drop by 3-7 percent, something that would add to the "range anxiety" of potential customers. By comparison, underinflated tires typically caused mileage in an internal combustion engine to fall by just 1.5 percent.

While testing such as this certainly won't endear EVs to the public, Napier said sticker shock likely will remain more of a hindrance. He said the Chevy Bolt carries a hefty price in the $38,000 range, while a standard ICE vehicle of a similar size—such as a Honda Fit or Kia Rio—cost more in the range of $18,000, or less than half.

With those type of economics, the spaces set aside for EV charging stations may stay empty a while longer.

Bruce Meyer is editor of Rubber & Plastics News and he sees rubber-related stories nearly everywhere he goes. Follow him on Twitter @bmeyerRPN.