I haven't had any problems with my DA22's. I do make sure that the little nut on the stem is out almost all the way when I mount the tire. Once I get the tire on, I push the stem up into the tire to make sure the little stiff part of the stem where it mounts in the tube is above where the tire mounts on the rim. Then I pull it down and put some air in, tightening up the little nut when it is pumped up a little. I just installed some Michelin Lithions a week ago and had no problems. These are the 4th set of tires I have had and none of them caused any trouble in mounting.