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I have an old Fuji road bike that I got a garage sale a while back. It's probably from the 70s or 80s. This summer, I've been trying to fix it up into good condition for some longer-than-usual rides (maybe 10+ miles, as opposed to just 4 or so). The old tires (27 x 1/8, hooked rim) were very worn, so I took the bike to a shop where they replaced them with new ones (32-630, 27 x 11/4 to fit schwinn s-6 or k-2 tubular rim).

The new tires say "inflate to 90 psi", which is what I was planning on doing until one of the bike mechanics told me that I was running them way too high. He said the tires and tubes could handle that 90 psi pressure, but that my rims (which are the original aluminum ones I think) couldn't take 90 psi. Instead, he advised that I keep the tires at 60-65 psi. I tried his recommendation, but the tires definitely seemed to bulging out a lot where they contacted the road as I rode it around. I feel like the tires should be more inflated, but I don't want to damage the wheels.

So, I thought I'd get some advice about the matter. I'm 165 lbs, and my rides won't be too serious for now at least. Just riding around mainly on some wide walking/bike paths we have in the city. There may be a few mile-long stretches of sidewalk, however. Any advice is very much appreciated!

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4 Answers 4

I can't see your specific rims from here, but plenty of bikes back in the 70s and 80s had rims that width capable of handling 90-110 PSI.

And I definitely wouldn't run a 1-1/8" tire at 65 PSI. I'd imagine that the rims, if designed for tires that narrow, should be able to handle 80 PSI or so.

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Running tires that narrow at lower pressure is bad, it will cause more problems than its worth. The tires will wear faster, you will pick up thorns and glass a million times faster. In the long run it would be cheaper and easier to get rims that can handle the higher PSI. –  BillyNair Jun 18 '12 at 19:33

I have a 1974 Fuji and I run my tires at 110-120 psi. Anything under 100 dosent work well on my bike. but if the tire says 90 psi I would put 90 psi in it.

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I will go further and say that what your mechanic told you is likely to be NONSENSE. See below for my analysis of why, but let me also say that people who ride below recommended pressure are more likely to give up and quit riding, because it's so much more tiring and frustrating!!!

See this article for "full details", but for hook-bead clincher tires, 27x whatever are the same bead diameter - so your worn-out 27x1 1/8 and your new 27x1 1/4 should both interface with your rims "successfully". Rims are not run anywhere near their strength limit as far as tire pressure goes - if they were, they'd fail if you hit a bump or curb particularly hard! But even then, instead of breaking they just go out of true but still hold the pressure.

If you want to do a (destructive) test to "prove" it - get an old wheel, a tire you're willing to sacrifice (with a good tube), and an industrial compressor with an accurate gauge. Now slowly inflate the tire until something goes bang. It will, and quite explosively (wear safety glasses). Now, take a look at what broke - see, it's the steel "bead" wire in the tire that snapped, and let the tire slip over the rim. The rim is still OK, and the tube would have held the pressure if the tire hadn't given way! (This experiment will fail more quickly with a very old used tire - the sidewall will explode instead.) For a tire with no "sidewall" issues, this experiment should allow for almost 2x pressure to be applied before the bead gives up the ghost. I honestly do not know what would happen in this experiment with one of those new-fangled kevlar-beaded foldable tires - if anyone tries it, let us know!

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I can't speak to the specifics of what your rim will handle, but if it were me I would be inclined to run the tire between 70-75 pounds. That should improve the ride as well as leave a margin of safety.

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