I believe you can run 28" tires on the stock wheels on a trail without spacers but you are getting pretty close. Also one rule of thumb is when adding a lift kit, those tuck the hubs in closer to the chassis..or inward, so most add spacers to get the wheel back out to the normal width. All spacers put additional side aka cantilever load on the bearings, bushings and ball joints. However 1.5" and less have the least noticeable effects on longevity.