Other than physical damage, it is probably the compound you are using. Color varies from manufacturer to manufacturer so you can use the color to know which load wheel you are using.

I suspect the "white cushothane xl" is the Superior XL compound with a 97A durometer (hardness). If you are using a cushothane ez (red), this the XL will outperform the EZ in high speed, long runs. They also make a XL AC which is even better for high speed long runs.

Alternatively, Stellana makes a very good wheel called the Lmax. My customer prefer this for most applications.

If you know the part number (SKU) we can confirm this information. Reach us at [email address removed] and we will provide you some options.

Thanks,
Bill