Figure out what rims and tires you want to run FIRST. The selection when it comes to wide rims is pretty limited especially when you get to 10"+, so if you want to use off the shelf rims it would be best to figure out what rims you want first, then the tires you're going to run on them, and narrow the axle so that the wheel and tire combo you want fits in your wheel tubs. You don't have to narrow the axle to do the mini-tub, but getting the wheels you want to use to fit may require it. And narrowing the axle may actually be cheaper/easier than having a custom set of wheels built, depending on what you want.
