I nave tyre model data for the tyres of a large motorcycle but need to model a scooter.   The former has 17" wheels front and rear with 120/70 and 190/55 tyres while the latter's tyres are 120/70 x 13" front and 140/70 x 15" rear.  

The purpose of the model is for dynamic simulation to use in controller development.   Therefore I do not need the model to be perfectly accurate, however I believe that at least a first order improvement in accuracy (relative to using data from tyres of the wrong size) could be obtained by simply applying suitable scale factors to the models inputs or outputs.  Thus effectively scaling the slip stiffness, camber stiffness etc.   Does anyone have any advise on how to do this or data comparing the characteristics of different sized tyres from which suitable scale factors might be derived?