Originally Posted by timmay70

Magenta tires are 32 shore and are a natural rubber foam
White is 25 shore and is a low natural rubber foam (synthetic blend)

The number refers to a hardness rating when using a durometer. There are different scales, so if you are using a durometer to measure your tires, make sure you are using the correct scale, and keep in mind that thickness of the foam will effect measurements.

good luck.