(Update 7-17. Bought a UV meter and UV detectors. See my comment below in replies) Got 10 pack for two bought a trailer. I use ranch. I wanted to reduce the UV exposure of the tires to increase their lifespan. The covers fit perfectly and stay on the tires in the strong and gusty winds we have here BUT I don't think these covers help keep the UV light from damaging the tires. Sunlight shines straight through the covers (I bought the white ones) and I'm a bit disappointed. As you can see in my photo, the sunlight comes straight through the cover in my spare tire and you can clearly see the shadow of my hand through the thin cover. (Update 5-17, I bought a UV meter AND UV detector beads (beads for that there is no better word) here at Revain and the meter and beads confirmed my suspicions. These caps DO ALLOW UV rays I then took a laser thermometer and measured one of my uncoated tires (same trailer, same side) and then took the temp of one of my tires that had been coated all morning but removed the coating and took the temp in less than a minute had recorded and these tires are nice does a good job of reducing heat stress on the tire but hasn't convinced me that my tires are 'protected' from UV rays.
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