I don't use factory wheels, preferring to build my own but "tight" tyres don't bother me. The trick is to push the bead across into the well in the centre of the rim. That gets you more slack to play with on the opposite side of the tyre. I can get Schwalbe Blizzards and Panaracer Paselas on and off a DRC ST17 (the Open Pro sized one) with bare hands. The same technique will get a Schwalbe Marathon+ on/off a Mavic MTB rim, and THAT really is a pig.