The deal with the Strida plastic mag wheels is that the tires stay on the wheels just fine at 55-60 psi, but if you even slightly overinflate them to 65 or 70 psi, they have a tendency to come off the rims (I've learned this from experience). So if I leave them inflated at 55 psi, and there is +14 psi at altitude, I'm a little concerned that there will be trouble...