I have not seen any white wheels that will fit a hummer. That is kinda out of style. Unless you are driving a sport compact. Do you ever plan on going off-road? If so go with an 18 inch wheel. If your a pavement pounder and it sounds like you are I would look at BFG's but I dont know if you can get the new ones with in a 20x35. I hear the Toyo's are pretty good on noise too. I have the 18x37x12.5 BFG KM's they are pretty good but I would say they are a little loud and not so great in the rain as they have no siping. However they wear really good.
Eric