Check out Nashbar's Streetwise tires... my friend has them on his folding MTB which he uses for commuting duty, and he says they have great punture resistence, and all the thing I've read have been good, and there only like 10-12 dollars. Although, I think they only go up to 26*1.75. Schwalbe Big Apples are supposed to be nice, but they are very expensive. I'd try the Nashbars out, though.