Spare tire size.

I recently went from a P275/55R20 stock wheel and tire to a P275/60R20 Cooper Discoverer AT3 4S. Is there any reason to replace the spare with a P275/60R20 ? I’ve heard there’s no need to change spare size since one would be used only to get to a tire shop. On the other hand I’ve read that it could possible damage the differential. Folks run donuts on cars ? Seems about the same to me. Any input would be appreciated. Thanks

 

You went from 632 revolutions per mile to 612 revolutions per mile. Just use the spare on the front without FWD engaged if you have it.

 

Can we fit a R20 series tire in the same spot on the truck?

 

This is what I've been thinking about too. My next mod will be different rims and tires (than stock) and wondering if I can put a larger tire on the spare rim under the bed. Would like to have something the same size as the other tires to prevent any damage.

 

yes you can. I have a 285/75 (35") on my stock steel spare wheel, and it tucks up under the bed nicely.

 

I have a spare 295/70 R18 on the spare metal rim. The diameter is a little over 34”. I had to modify the mount for the two retaining brackets to make it fit properly. Some remove completely and some bend these brackets, but I cut out the inner most rivets and added 1/2 spacers with new bolts to tilt them back enough for the tire to fit.

 

Thanks for the replies! This really helps....now to decide if I want to stay with 20's or go to 18's....

 

you could always find the comparable size in an 18 for the spare, if you go with 20 for the truck.

 

It'll be fine, your differential is meant to make up the size difference and worst case run it on the front. I wouldn't think twice about swapping my stock spare onto the rear and I have 35s.