Has anyone here successfully installed a Conti Ultra Gator 700 x 25 onto a Mavic Open Sport w/o having to use levers to perform the final push onto the tire?

I am changing back to 25s from my Marathon Supreme 35s. I just flatted 2 tubes putting the tire back on.

Any idea what I'm doing wrong, other than not being the Incredible Hulk? (I've installed the Gators on my Salsa Delgado rims many times, so I'm not completely incompetent, just currently.)