Mine fit pretty loose on speedway 70s but i havent had any issues while riding. I am using surly tubes and i found the best way to mount them is to put enough air in the tube that it helps the tire hold its shape on the rim and then carefully center the bead on the rim on both sides as you start to inflate the tire.At about 20-25 psi the bead seats but it doesnt (pop) on like a smaller tire would.J-No said: