For anyone who's runner came with 31s from the factory,
what size is your spare???

 

I am assuming mine came with them even though my door says 225. My speedo is reading correct with the 31's, so unless the guy before me recalibrated it, which I doubt, it came with 31's.
But my spare is a 225.

 

a good way to check is to look at your rear bumber hangers and bumper runners that came with 31 use a larger bumper hanger to clear the spare, the spare is a 31. I got rear ended a few years ago and a buddy of mine at the dealer gave me a parts list for the rear bumper assembly when I bounced it off of the isurance part list the bumber hangers part # were different. I did some research and the insurance list of parts(cheaper) was for a runner with 225 tires.

hope it helps,