What’s on your wheels?
Not long ago I wrote an article about losing the fourth bar on my 2012 Nissan LEAF. When writing that article, I noticed that our fuel economy was 3.1 miles per kilowatt hour, which I had never really paid any attention to before. This is pretty low compared with many EV drivers that can achieve over 5 miles per kilowatt hour, extending their range significantly over mine. I know we drive with a lead foot occasionally, but this low efficiency didn’t make sense to me. So after thinking about it a bit, and wandering around online I went outside and looked at the tires. This story is a result.
We bought the car last year and it had gone through a local car dealership for reconditioning. As is often the case, they replaced the tires with the cheapest they could find. The tires that ended up on the car are Goodyear Assurance All Season M+S (mud and snow) tires. Just what I need to tool around the Greater San Diego area. Mud and Snow tires have a more aggressive tread pattern and a tread compound designed to optimize grip, not roll down the road easily. Original equipment tires on the car were low rolling resistance Bridgestone Ecopias. So the question becomes, how much can a tire impact fuel economy, and range, on an EV? This is what I found out with a little bit of research. Many others have studied the impact of tire rolling resistance from the U.S. Department of Energy to over-the-road truck drivers wishing to lower their operating costs. I also found some other interesting info from an off-road vehicle site that proved illuminating.
The Alternative Fuels Data Center found that installing low rolling resistance tires can improve fuel economy by about three percent on light duty vehicles, in other words, passenger cars. Just a ten percent decrease in rolling resistance can increase fuel economy by one percent to two percent. Heavy-duty vehicles can see improvements of over ten percent.
Perhaps the most interesting example I found was on an off-road vehicle site. They were curious about the same thing I was – how does tire type impact fuel economy. So they did a real-world test with a Ford F150HD – not the most fuel efficient vehicle on the planet. They tested two sets of LT (light truck) tires that were designed for two different purposes. One set was a street-oriented all-season tire while the other was an aggressive tread all-terrain tire. Their test discovered a whopping fifteen percent difference in fuel efficiency.
So I found that while our lead foot is a factor in some of our poor fuel efficiency, it is not the only factor. This tells us is that when you need to replace your EV tires (or really any vehicle that you’re interested in fuel economy) the type of tire that you chooses matters. If you are using less energy to roll down the road, you can roll farther. With a little online research you can find the most fuel efficient tire for your needs.