ok well , if i was going to buy 265/75/16 tires for my stock rims , but instead decided to go ahead and buy 15x8 steelies for these new tires, would i have to change anything on the tire size(besides the 16 to a 15). it would have to be a wider tire right? sorry if this sounds stupid but i hate talking/learning/discussing tire size info.

or should i just go with standard sizes , 31x10.5x15 that'll fit , right , without a lift?

You really should stick to stock wheels because they have a unique offset that no aftermarket wheel has. If you do decide to go w/ different wheels I'd think you'd need to drop down to at least 31s (rather than the 32s you were planning on). Even 31s may rub quite a bit w/ the different wheels.

You need the stock backspacing unless you want to do alot of trimming. I've got tires that are 33.1x11.3 on a stock height truck. The backspacing of the stock wheels works better than any of the aftermarket rims.