Its a compromise between stability and articulation.

If you make the tires stick out (Illegal in states such as NJ for example...) it gives a wide stable stance...

If you want to preserve up travel/articulation, you need the tires to be able to make it up into the wheel wells.

The rears are even trickier...as what will stuff on straight compression can rub on opposite droop compression.

So my 5.25" BS rims let me stuff the rear's easily despite my big 'ol 305/70/16's (A bit wider tread, and a bit taller diameter, than a 33x12.5/15)...

But, on opposite side droop, the stuffed tire rubs the INSIDE of the well, against the frame, when the other tire is fully dropped down.

So - If I have enough BS to be able to stuff both together (A landing for example...), I'll rub on opposite day...

If I space them out a bit, I can do the opposite droop better, but, I'll rub on normal compression, etc.

For the fronts, less BS = Rub, no matter what.