Forgiving is a good way to describe my experience with the original Rival (non-S). That was helpful in some scenarios but made it more difficult to figure out what the tire really wanted.

I suppose it doesn't matter much until the Rival S is available in a 265, but I'd still like to try them some day. If I can find a used set of 255 Rival-S I may put them on my 17" wheels to try them out.

 

I have talked/read about how this cooling actually works. Apparently, you have two things that are worth talking about:
1. cooling effect that comes from difference in temperature between the rubber and water.
2. cooling effect from evaporation process that happens when water goes to steam.

From what I know, more of the cooling is produced from #2, which point that using we don't have to go to colder water since it might take longer for it to evaporate. For the same reason, I have stopped using ice in my cooler long time ago...

 

You are correct, he greatest requirement for energy (heat) is when the water turns to steam. But if the water starts off colder, it requires more energy (heat) to get to the point of turning to steam. So, iced water should still be better as it stays on the tire longer and absorbs more heat.


Exemple: When you burn your finger, you run it under cold water, not room temp water. Or put ice on it.

 

The whole point was that you need to try to maximize number of evaporations...starting with cooler water would make this value smaller....

 

ever the contrarian. that assumes the tire has to turn the water into steam (212F). otherwise, if the tire is in the sun or just rolling off the tire, cold water is better. likewise cold water cools me down faster than warm water. I don't complain that the cold water takes longer to evaporate than the warm water. it's more the breeze/wind on it than evaporation

 

Water doesn't have to be at 212 to evaporate. If it did, your bath towels would never dry.

 

got me there

 

A quick update here, post-Crow's NT. 265s, with us driving (our best) we still lack the pace to keep up with a well driven 350Z (dry, sticky concrete). That said, given Jeff's cone trouble on day two, I could have won, lol (my quickest run had 0.8 seconds worth of massive screw-ups). If Jeff's quickest was clean on day 2 like it was on day 1 it would have been a serious ***-whooping. [edit] I'm going to back off this statement a bit, maybe Jeff had a bad Sunday but if I hadn't mucked around on my 3rd run I think I could have caught his fastest scratch time (61.9~ish). On Saturday though, I don't think so.


After looking over our data (Solo Storm), here's a tip: if you make an early mistake on a run, try not to compound it ;-)

 

Tasha's runs from this weekend at Crow's, she was killing' it
and the courses were amazing, so fast, so much grip.

 

^^^ Holy shnikees, that looks really fast and really fun-- quite a bit of time spent in 3rd gear!

 

Looks like 265s might be more helpful than we thought at first...

 

Idk what size/compound tire you run on your car, but on my car, I noticed a good gain in grip going from 255/40r17 Dunlop Z2's to 265/35r18 Bridgestone re11's. Even though tire rack show their tread width measuring as the 265 re11 being "narrower", I really feel like they have more grip.

 

RE11 or RE71R?

 

RE11, they're just my street tires. So I can't quantify the feeling of more grip with any kind of lap times...

 

sorry if this has already been answered - do the re71r 255/40-17s fit well on the stock 17x8s?