I've been looking around at some machines in action and doing the things I need them to do,and it seems that a cushion tire should be fine.It would make sense to have as large a diameter tire as I can get,especially that some of the lifts I have seen/used have had a small diameter rear tire. Any tips for finding a larger diameter tire unit? Is the diameter soley dependant on weight capacity? I mean is there much to choose from in a 4000 or 5000pound machine?