Originally Posted by nitrobeast
Is there a "magic" number you shouldnt go past?
Nitrobeast - it's not really that the shore of the tire changes as you go lower (in actuality, it doesn't. I have a durometer and the only way it "changes" is if it is too shallow for the probe to penetrate before hitting the rim. Take the remaining foam off and measure it by itself and there is no change. . .)
What happens is that as you get a smaller and smaller tire (wear off the foam) you lose the amount you can flex - less sidewall, less flex. There is a corresponding effect - the less flex, the quicker the steering response. . .
Same with full size cars, btw - it's why racers run lo-pro tires: their traction is in the suspension and their slicks. they want the car reacting as QUICKLY as possible to their inputs!
In any case, you lose a bit of grip by losing that flex AND since you're reacting more quickly to steering input, it effectively means you have less traction.
The tire didn't get harder (higher shore rating) - you just have less of it.
This can actually be a benefit to you - if you find a size that you just love, take a note of it.
If you're in a tough race, use tires that are of that size or just a smidge bigger (so you'll wear them down and be PERFECT in the middle of the race!) and kick his ass!
We used to run a slightly larger rim (can't find them anymore
) so that our tires, when they were at a "normal" overall diameter, were lower profile (big car principle) so we had quicker response.
In any case (and because I ramble. . .) just remember:
smaller sidewall=less flex and less traction but quicker response
larger sidewall = more flex and more traction but more sluggish response