Originally Posted by RT-BRZ (Post 3564491)

All very interesting data. The only thing that's tough to get past is that the 225 tire at the same aspect ratio is taller than the 215 tire. While the difference is pretty small, there is a difference there and it does make the results suspect. I'm not saying I doubt them but there is enough variability to make more questions.

The wet results are not surprising. Water creates drag and a wider tire is going to have more of it.

In a straight line the narrower tire is going to be faster because of less drag. The wider tire has the opportunity to make up for this in turns where the lateral grip is greater. In the wet the water acts as a lubricant and therefore reduces lateral grip for everyone which effectively nullifies the advantage.

It would be kind of neat to see a track map of speeds/times comparing these tires against each other.

Originally Posted by RT-BRZ (Post 3564491)

All very interesting data. The only thing that's tough to get past is that the 225 tire at the same aspect ratio is taller than the 215 tire.

Originally Posted by MacSpeed (Post 3565077)

The TR test are better than nothing but still need to be taken with a grain of salt.



They do not adjust tire pressures for one. They run what the door says for psi. once that is changed and FSB is added to the mix like street class autox plus bump stop tuning and shocks, these results get thrown on their head.



Don't get me wrong, this is all cool data but I would be careful pulling hard absolutes from it.

Originally Posted by cmiovino (Post 3565053)

Speaking in terms of autocross only, it's common that everyone is putting as wide of a tire on as possible. All our second gen guys (and there's a lot of them) are running 245's and even 255's on a 7.5".

Originally Posted by Scargod (Post 3575820)

What I'm curious about, and don't see much about, is what horsepower does to our tire selection. I can only assume that people are stock unless they say otherwise.
Then you start gutting, lowering, adding aero. All that is not clear unless stated, which it seldom is, or perhaps you go digging for the poster's info.

I've seen people talk about running 255's on road courses. I think some (most?) have turbo's.

I get 230 HP from my 2022 BRZ. I've no rear interior, but I have a wing and splitter. I'd guess I'm under 2,800 with light 17" wheels, rotors, coilovers, lighter exhaust.
I'm very happy with the performance of my 245 F1 Supercar's. Good lap times.
So, could there be an advantage for me on tighter, shorter courses with 255's? If it's only 50-75°F will there be an issue getting them up to temp?
Goodyear doesn't make an F1 Supercar tire in 255 though there are tires like Falken's and Kumho's, but is their lesser traction performance outweighed by their larger surface area? I'm not going to go to Hoosiers or similar that cost a lot for the laps.

Originally Posted by GrandSport (Post 3599859)

If you can't get enough negative camber to get the tire flat, it really doesn't mattter how much tire is not touching the ground (or doesn't have significant load).

So yeah, when you're only riding on the outside inch of tire around turns because these tires are so grippy these days, regardless of the tire width, the tire that is 10% lighter will be faster.