I have an '02 2500HD and would like to use the factory rims with some 12.5" tires (with small lift) until I decide which aftermarket wheels I want. Will the
OEM wheels (16") accomadate a 12.5 tire?

Yup it'll work. but its hard to find someone that would put them the stock rims cz therye only 7" wide. You probably shouldnt do it for too long though.
These are 315/75/16 or 35 X 12.5

http://i89.photobucket.com/albums/k219/Oleg_Yakymovych/3157516BFGAT3.jpg

So are you running 315's on your 1500 with much of a lift? They look great, any rubbing?? Thanks for the info.

So are you running 315's on your 1500 with much of a lift? They look great, any rubbing?? Thanks for the info.

At that time it only had a 3" body lift with a little crank and a little trim of the lower valence. With stock rims I had no problems with rubbing but when i got aftermarket rims i had alot of trouble turnning so i had to get a 2" keys and block lift and now i have no problems.

3" body lift and 35s:
http://i89.photobucket.com/albums/k219/Oleg_Yakymovych/3157516BFGAT10.jpg

3" body lift + 2" keys and blocks lift:
http://i89.photobucket.com/albums/k219/Oleg_Yakymovych/flexin024.jpg