Tire Rack just did one of the best tire tests I’ve ever seen. They tested the same tire (RE71RS) on the same car (2022 BRZ) with different tire and rim widths. Please go read their article because there are a lot of useful details there. I’ve copied the graphs below. But let me summarize.
- If all you have is 7″ rims, you’re faster on 225 than 215 or 245. Wider rubber isn’t always better. And in the rain, you’re better off on 215 than 225 or 245.
- If all you have is 8″ rims, you’re also faster on 225 than 215 or 245. Except in the rain, where once again, you’re better off on narrower tires.
- If all you have is 9″ rims, you’re still fastest on 225 but 245 is close. Maybe with a 10″ rim the 245 will be the top dog. And again, in the rain, narrower is better.
OK, so how does any of this make sense? There are so many unlisted variables here that all you can say is that on this day (actually 3 days), with this car, these tires, and these drivers, this is what they got. If the day was much colder or much hotter, the results may have been different. Maybe the narrower tires got to a better temperature in the rain and on a hotter day that difference would disappear? These tests are difficult and time consuming. However, they are also essential because the results are impossible to predict. Thanks Tire Rack. I’ll probably buy my next set of tires from you because of this test.
The big take-aways for me are the following:
- More rubber isn’t always faster
- You’re almost always better off with a wider wheel
you suck at racing 