Originally Posted by
ThermionicScott
I'm betting it's the rims. If they're steel or otherwise have non-hooked sides, they won't hold onto the beads as well, no matter what the tires are rated.
Originally Posted by
nlerner
Yup, non-hooked bead rims plus Kevlar bead tires = blowouts above 70 psi or so.
Originally Posted by
JohnDThompson
+1 this.
Originally Posted by
juvela
+2
Originally Posted by
Trueblood
Wow, ok, thanks everyone, yes older Araya rims, perhaps original to the bike. Probably non-hooked. I would like to keep using the wheels as they are. Must of worked somehow back in the day. I was going to go down to 80 psi next but it sounds like 70 is the max on these.
...+whatever. I've recently done this with Araya rims with what appears not to be a straight side, but a totally inadequate bump to retain the bead. I ran through two tubes and part of my remaining hearing before it occurred to me that maybe these were just barely old enough to be relatively straight sided rims (they are not 100% straight, but not much is there to hold the bead.)
My original tyres were some specialized low end things, so I switched to some Panaracers and lowered the pressures to 70psi rear, and 65psi front. So far, so good.
I'll probably just rebuild the wheels with a Sun rim when I get the chance.