Eric,

Welcome to C&V. Glad you joined.

The old style hookless rims usually only let you get to about 70 psi or so. The variables do depend on the tire and the rim. Generally the cheaper stiff tires with a wire bead work the best, but those can also be a little "big" in the inside diameter, and thus slip off the rim easier. Try mounting the front tire on the back rim and see if it still comes off. If it does, take it back and ask for another Kenda. Best of luck.