31" tires & 3.08 rearend! How many problems?

[Sooner1970_K10]

I currently have a 3.08 rearend in my k10. I have decided to make do with my original rims and no lift kit untill a later date. The tires on the truck are mismatched and ratty looking. I decided I atleast wanted to replace them. I am also going to get the old rims stripped and powder coated (white) for around 40 bucks a piece.

Currently the truck has 235/75/15 which is around a 28" tall tire and 9"ish wide.

The tire gear ratio guide states that anything over a 28" wheel is not advised for a 3.08 rearend.

Mind you, this truck is only for driving to town and maybe an occasional small load. No hauling or offroading will take place.

Question: Am I asking for trouble if I run 31x10.50x15 tires on a 7" (stock) rim with a 3.08 rearend? Will it hurt anything, handle bad? How much performance decrease would I be able to see.

Question: Any advice on the best place to get some BFG's in the above size? I will call around and find the best $$ price but as far as service or warranty what would you guys suggest? In the past I have compared 4wheelparts local store, sears, and a couple of the local tires shops.