For the suspension Gurus

Hi, anybody have any data on the effective spring rates of tyres used on their GT40's or replicas?

An interesting question... In 65 pages on tires in Race Car Vehicle Dynamics (Milliken), there isn't any reference to vertical deformation - but many pages on lateral. Certainly, the vertical rate is wildly non-linear past a relatively small deformation. Maybe any influence is negligible - or it's just too complicated to cover!
Hi, thanks for your thoughts!
Interesting how the subject is ignored, the compression of a tyre my well be in the order of 10 times greater than chassis distortion, for example.....
I have read some related stuff in RACERCAR ENGINEERING, relating to the old 2 liter touring cars..

A few years ago the main racing category here in Australia went from a class with many tyre suppliers to a class with a single control tyre. This left many teams disadvantaged as a result of not having ever tested with the remaining tyre. An interesting discussion at the time was the fact that these teams needed to not only tune the suspension to allow for the different grip characteristics, but also to the spring rate of the tyre. A bad combination could set up nodes in a standing wave causing the vertical wheel motion to alter during a single sweep.