I have 305-55-20 tires on my truck, its gonna happen one day no doubt, and its gonna happen when im 6 hours away from home...no way m i gonna put my stock spare on there and tear up my gears....i would really like to get another rim and tire and throw it underneath...the 1500's have 20's under there y cant our trucks?????

 

I fit a 35x12.50x16.5 under mine no prob. Overall dia. is about the same, I believe

 

You can put a 35" tire under your truck if its not new, A old one will work great because its smaller then 35". The rails are just a little smaller then 35"

CRIS