Backspacing/ tire size

[David67]

Hey guys,

I'm hoping to be able to order my wheels/tires today so I can install the 5 lug axles that will be coming in this week. I'm trying to finalize the measurements so that I can be sure that everything will fit.

I've decided on the American Racing TTII's, 18x9.5 in the rear and 17x8 in the front. Between the hub and the bed (stepside), there is 6 in. of clearance. Between the hub and the outmost part of the fender, there is 7.25 in. with 6.5 to the inmost part of the fender lip.

The two main backspacing options that I'm looking at for this rear size wheel are 4.31 and 4.54. The main thing I am concerned about is the tire clearance. Does anyone know how much further a 275 or 285 tire would stick out on each side of the wheel?

Also, can anyone help with determining the tire height or what they think would look the best (with a 4/6 drop)? For instance, if a tire is 275/50/18, how is the 50 determined?

Thanks!