got 4 under mine. 1 bearing goes why would i care,2 goes im worried.and as far as sidehilling go try bending your track. hmmmm can't right! rolling resisentce(sp) haha! just saying!
Stock wheels have 12mm wide x 42 mm o.d. bearings. Three stock wheels = 36 mm of width. This kit has two 15mm wide x 52mm o.d. bearings ( bigger rollers in the bearings ) Two wheels = 30mm of bearing width.
Two wheels allows for better maneuvrability and side hilling. Slightly less total bearing width, but larger o.d. bearings. Basically, it is a "light duty" bearing vs a standard duty bearing.
The advantages I have found from the larger diameter wheels is that the track seems to roll smoother past each of the fiberglass bars in the track. i.e. - There seems to be a bit less rolling resistance with an increase in wheel diameter.
As far as the 2 wheel kit... there are still stiff fiberglass bars in the track, that won't bend much. It will allow for a certain amount of flex, but not a ton. I personally REALLY LIKE the looks of a two wheel kit, and I really don't think there is a downside to them (short of blown bearings), but I think wholesale gains are minimal as well.