Our wheel covers are like heavy soft vinyl ( don't know what it is) and has layer of woven padding on the inside. Ours happen to be off-white and are pretty heavy duty. We have had them about 8 yrs, but don't remember where we bought them. Maybe online. My understanding is that they block UV rays and also ****** some of the heat that would otherwise build up on the black rubber tire. They are not hot to the touch even when sitting in full sun if you touch them, and neither are the tires underneath.