37" will clear with no lift, but it'll rub when at full stuff. I'm guessing by the fact that you're even considering 24s that this vehicle is a parking lot pimp and therefore full stuff is a non issue. Your biggest concern is going to be tire width and wheel offset. Too wide a tire with too tight an offset, and you'll rub.
On a personal note: 37s look like rubberbands on a 24" wheel. I think they look terrible, but its not my truck.