Quote:
Originally Posted by cstreit
Interesting correlation.
FWIW I did try the A6's last year, for the first 20 minutes they were great, but after 20 minutes they were SHOT. no grip, greasy as hell.
This confuses me because that suggests they are overheating (R6's do this too, but to a much lesser degree). Then WHY am I getting 145 degree readings some times?
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I think it makes some sense to me:
The A6s, being stickier, allow for more friction. You get them up to ~150 degrees and they let you pull ~1.3 Gs, meaning you're putting ~2860 lbs combined load on the contact patches, meaning they get hotter still (170 degrees?) and overheat.
Same situation with the R6s and you get them up to 150 degrees, but that's still below the point where they get really sticky, so you only pull ~1.1 Gs, put ~20% less load on the contact patches and thus 20% less energy in, and you can't get them any hotter.
So you overheat the A6s (170+ vs the ~150 ideal) and can't get enough heat into the R6s (150 vs the ~190 ideal).
Now if you took the A6s and made them wider, ie spread that 2860 lb cornering load over a wider area, you'd expect the tire temperature to go down roughly in proportion to how much extra area you added. It's not quite this simple, but if you had a 100F temp increase before, then increased tire area by ~10%, I'd expect a slightly less than 10% drop in tire delta T. So your previously overheated 170 degree A6 might cool to a passable 160 degrees, and suddenly your tires don't go off after 20 minutes, but rather last the full session.
The trick, as I see it, is not to fall into that gap between tire compounds you're in now. If you had a car with a normal tire to weight ratio (say a GT3 with ~75 lbs per inch of tire) the R6s would either be overheating or just right. That's why that compound is designed the way it is- most people have that type of tire to weight ratio. I'll bet the full Dunlop slicks are designed for true race cars with closer to your tire to weight ratio, and thus would work better...
At least that's my (amateur) view of the problem...
-Pete