In theory, they are suppose to not allow the plane to bounce or reduce the bounce on landings. Since this is the beginner section, most trainers bounce not because of the wheels, but instead because of the landing gear itself. Low bounce tires can be used if this problem is big. Normally, working on your approach and landings reduce the bouncing of a trainer. The tires are made from a shock absorbing material. I've seen many new pilots change over to low bounce wheels with no difference noted. I mentioned eariler, practice will reduce this tendancy.