[Stocker]

In fact, 10" is the correct wheel width for a 12.50-width tire. You shouldn't have any fitment issues with a 4" lift. The truck might actually look better with 35/12.50s instead of 33s, but the taller tires might have minor clearance problems.

Back to your 33-12.50s on 10" wheels. I'm running 33/12.50-16.5s on 9.75 wheels, with 2.5" Softrides. No problems at all, but my front fenders were notched many years ago to clear a different wheel/tire combo (before the Softrides). Just eyeballing it, I don't think there would be any problems even if the fenders weren't notched. You should be fine with your 4" lift.

Plenty of guys run 33s on 8" wheels, which is a bit narrow but it seems to work okay. Upside is they won't stick out as far up front, and your bearings will be happier.