I run stock rear wheels and 32" BFG's at each corner on my 1000X-4. Have not had any issues. I do this so that I can carry only one spare tire to minimize weight and rear wheels are easier to find than front wheels.
Most (75%) of my riding is on super rough southwest trails and rock crawling at less than 15mph. Therefore I do not really deal with tracking issues associated with running different front/rear track widths at higher speeds. If I start riding a lot of high-speed trails, I will put a set of 1.25" spacers on the rear but do not foresee this happening soon.
My tire pressure is 10psi while crawling and 15-18psi on trails and I have not popped a bead or broken a wheel. Eventually I will go to a 34x12 tire and some sort of wider long travel suspension (and gear reduction) with stock rear wheels.