Yes, that's really the problem - installation can be trickier if the tube is too large and you may have a blowout if part of the tube gets pinched between the tire and the rim. But I've sometimes used tubes that were way too large without any ill effects. That includes using a tube for a 27" tire in a 20". It had to be folded over on itself but the wheel rode fine and was in daily use for a long time before I got around to getting a tube of the proper size.