Quote Originally Posted by SeverAMV View Post
ill probably appear noobish by saying this, but normally bigger wheels means lower profile tyres, which means less air required for same tyre pressure and more responses from bumps on the road, so in that regard it could affect damper choices, altho not by much. i went from 13s with high profile grippy tyres to 15s with low profile grippy tyres and the response difference when you go over a bump is more noticeable, with the 13s and the bigger tyres being more floatier, and the 15s being more responsive and slightly annoying on bumps.
All else being equal, I think it's less the volume of air (i.e. the size of the air cavity) inside the lower profile tyre than the shorter side wall being inherantly stiffer (than with a higher profile tyre) that increases response to steering input as well as increasing harshness over bumps etc.

Tyre profile (and psi and sidwall stiffness generally) affects overall spring rate because the tyre is effectively the first of two springs in series (the tyre, then the coil spring itself), but it's hard to predict what the affects of increasing tyre stiffness might be for damper rates because the tyre is an undamped spring that is typically very much stiffer than the coil spring, which is damped.

Note that in F1 cars and similar, that the tyre is the major spring in that it's usually (always?) softer than the coil and accounts for the majority of the 'suspension' compliance.