I have some schwalbe marathon green guard (27x1 1/4) on my araya alloy rims on this '76 nishiki . I was wondering what psi should I pump them up to without having any issues ? (Araya w/o HP 27x1 1/4 rims)
I believe those rims aren't truly hook-edge by the modern definition of the term, but they're not exactly straight-walled, either. Sort of a small bulge at the edge, maybe hook-edge-light would be a good way to put it. I don't think anyone can tell you exactly how much pressure would be safe with that combo, in terms of max safe pressure. That would take trial and error, hands-on. You might be able to safely inflate to the tire's labeled max pressure, or maybe not. You'd likely not want to go quite that high anyway. Again, my guess is that it's not a truly modern hook-edge rim, but better than a straight-walled rim.
.......unless they've changed since the last pair I bought, Schwalbe Marathons are one of those
tires that are very hard to mount, primarily because of the very tight bead diameter, so I'll go
out on a limb and guess that you're safe up to the maximum stated on the tire, unless your rims
are genuinely lacking any bead seating hook or groove whatsoever. AFAIK, mid 70's Araya rims
are as stated above....they have some hook to them.
86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.
I've got a pair of those rims in the garage that were on an early 70's Takara. (shiny steel)
Back before I knew what a hook edge rim was, I used to inflate them >70and occasionally near 90 PSI, with the cheap Cheng Shin tires that you'd get at X-Mart.
They are a somewhat difficult rim to mount tires on, but probably not the worst.
I won't recommend a max pressure, but personally, I'd have absolutely no qualms going to 75 PSI if I was using them.
I just looked at them and see no sign of a "hook".
Yeah I don't see a hook , it's more of a bump thats slightly there and extremely hard to notice by eye . They're inflated to 85 psi at the moment and haven't had any trouble in the 50 miles I've used them. schwalbe recommends inflating them 5 bar?I'm assuming around 80 ish psi , on non hooked straight sided rims .