Originally Posted by
alcjphil
80 psi is very high pressure if the bike in question has 27 x 1 1/4" tires and rims without hook beads. 60 - 70 psi for a setup like that would be closer to the realistic maximum
Still it's not too high a pressure. Or at least it shouldn't be material to the OP's tire blowing off the rim. Or I suppose not the important take-a-way piece of info. The important part might be that the tire just wasn't properly seated.
Though till the OP replies, we won't know. I'm just speculating.
I had to get my 27 x 1¼" up to around 150 PSI to intentionally blow them off my chrome plated steel smooth be rim when properly seated. The accidental times they blew off was IMO, because I didn't have the bead properly seated yet. But those were still better than 100 PSI when they blew off.