is it better for the spare to use a cover??? thanks

 

It will certainly help against UV damage, but being that your in Washington, you probably don't have too much to worry about. If you want to show the tire off, then don't get one. On the other hand it does help protect it, not only from the sun and elements, but also it helps a little with protection from theft as it's out of sght, out of mind type mentality.

I'm in AZ and will certainly have one as it's hot, dry and lots of sun, about the worst combination for tires.

 

why is UV damage an issue? arent the other four tires susceptible to UV damage as well?

 

Use some 303 Aerospace protectant on the tire. It has UV protectants in it.
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