Before you think what an idiot. I asked this question because if you go to gbodyparts.com they have a 28x12.5 et street mounted on a 15 x 10 rim.
According to MT website a 28x12.5 has a sidewall width of 12.6. Now according to BFG website thier 325/50/15 has a sidewall width of 13.1.
A .25" difference on both sides seems like it might work. Has anyone at least tried to stuff it in there?