Just wondering if anyone has put the factory spare cover in the washing machine. I have one to use but it needs a cleaning. It’s not super dirty but I figured it would be easiest to just machine wash it if I could. Lol

 

I had a 1978 CJ7 with a spare that never got rotated in and remained uncovered. When I needed it I found that it had dry rotted and was full of micro cracks. I always rotate them in since that unfortunate incident, but as it has been stated, to each their own. The cover will help with longevity as the spare is not in direct sunlight, although if you rotate it in, it won’t be out long enough to matter. The wheels in ground contact get shade from the vehicle and are constantly changing position. That uncovered, unused spare sits back there in the same position baking.

 

^^^ And it's not just visible UV damage (cracks and dry-rot); Probably wouldn't have mattered on a CJ7 () but on a heavy hi-po vehicle like the Defender a tire that has aged out, even if it's seen very little UV, will have considerably less grip than it did when new, owing to the hardening of the rubber compound. Read up on the actor Paul Walker's death ride in his new to him Carrera GT with original 10 year old tires.

Sure, they'll probably still hold air if you keep a spare back there for 8 years, but it's going to be considerably less of a tire than it's 3 brothers if you do have to press it into service.