Quote:
Originally Posted by JCz04Bimmer
I may just have to go with a 265F and 285R set up. 
What are your thoughts on that? Other than the fact that on the street tram-lining will make me want to take a bus... |
I'm of the school of thought that wider isn't always better when it comes to tires. The available grip is mainly determined by the frictional material (tire compound) and the size of the contact patch. The size of the contact patch is determined mainly by the mass placed upon the tire and the tire pressure and has little to do with how WIDE the tires are.
The main benefit to wider tires in performance applications, is that there's a bigger surface area to cool-off and therefore the tendency for them to over-heat decreases. There's a couple of argument here, that if you're not on the edge of overheating your tires, you're not driving fast enough. I'm again of the school of thought that if you're overheating your tires, you're not driving SMOOTH enough and therefore you're not driving fast enough.
The other draw-back, is that wider tires are heavier. So if your driving style and your car's weight isn't enough for you to constantly be fighting the tires from overheating, going wider isn't going to help much. On a car like say, the E92 M3, you can put 275+ all around and I will probably still overheat the tires due to the weight and available power. But on a car like, say, a Lotus Exige S, putting anything larger than 255mm would probably mean you're unnecessarily degrading the performance of the car. But that's just my opinion, of course. I don't have actual scientific data to back that up.
However, if you subscribe to "Grassroot Motorsport" magazine, I believe 2 months ago they did an article comparing different width tires on an autocross course on a Mazda Miata, and found that wider tires, up to a certain point, start to degrade their lap time. And about 4 months ago they did an article trying to get a Subaru WRX Wagon to handle 1G or higher with street tires, and when they put on new, wider tires their lateral load readings actually went DOWN.
I can only speak to my personal driving style and experience, and I find that 245F/265R seems to give me more than enough heat dissipation to stave off overwhelming my Toyo R1-Rs, but 225F/255R couldn't save the OEM Contis from nearly melting (when I pulled into the pit, I can put a finger on the tire and it would leave an indentation and the rubber was so malleable that you can almost see my palm print on it).
Then again my 245F/265R combo wasn't enough tires to allow me to keep up with my instructor friend at the California Speedway event. He was driving an E46 M3 shod with 275s all around an otherwise stock car. But that doesn't mean squat since he does have 10+ more years at this than I do.