Close to stock, maybe a 33" class, depending on OEM size. Hence a lot of lifted truck owners running 33's or bigger drop the spare altogether to save weight. If you ran 33's, and had a stock spare, it would be like a donut and not technically that safe to run for very long, if at all. A 35" tire will definitely not fit underneath the truck.

 

I had a 33x12 under my old 2008.

 

I finally have larger tires installed on my truck, 295/65R18 = 33.10 x 11.80

I need to get a close sized matching spare...........for the 17" spare wheel

Spare P265/70R17 = 31.60 x 10.40

Again, the spare tire width does not concern me, just trying to get close to the 33.10" diameter

Finding a common size 17" tire for a spare is also a concern

275/75/R17 = 33.20 x 10.80 (Tire Rack say does not exist)

33 x 11.50R17 does not exist

33 x 10.50R17 size does exist, but only one make/model

Other option is to find a used 18" rim on Ebay ? (but that will also be $200 ontop of still needing a tire)

255/75R17 = 32.10 x 10
too small

255/80R17 = 33.10 x 10
right fit diameter

Toyo sells an open country in the 255/80R17 for $215

I think this will be my cheapest and best option

 

On my 2017 Silverado, I had a full size spare. I had 20’s with 35’s. It fit perfectly underneath. The only thing I had to use was a hub centric ring for the spare tire hoist.