Whatever you do, be careful with going to oversized radial tires. The sidewalls of the radials are designed to be the right shape/stiffness only on certain sized rims... check the tire for what size rim it will work on, a 180 radial on a 2.75" wheel is not a good idea, it won't have the right shape and may do weird things to the handling of the bike, especially when leaned way over.