First, this sounds like one very cool tandem. Now, back to the subject.
It's important to recognize that the ability of clinchers to handle 120 psi pressures--which is close to the limit even for modern rims and tires--came from the precise standardization in sizes provided by the ISO standards. Remember, 60-70 psi was normal for clinchers back in the 60s and 70s bike-boom days. The main reason for tubulars, in the days before this standardization, was that they could handle much higher pressures and achieve significantly lower rolling resistance than clinchers. I don't know when your rims were produced, but I suspect that most older 27" rims predate these standards.
So, if you want to put 120 psi in a clincher tire on an older rim, you probably will need to experiment a bit by trying different tires; this might get expensive, and, in the end, might not be successful. I do agree with the suggestions of using wire-bead tires. I'd suggest, instead, keeping the pressure much lower and using a large enough tire so that it doesn't matter so much.
Steve Maas (definitely starting to feel like winter, this week, in) Dublin, Ireland
>I can't seem to inflate Conti Ultra Gaterskins on my 27" Super Champion 58 rims above 90 psi without the tire blowing off the rim. It is on a tandem so 120 psi or so would be nice (we are no an especially lightweight team). Has anyone found a modern tire that will stay on this rim at these pressures? The SC 58's seemed to be a quasi hooked bead rim. I think that I recall that Conti Sport 1000's were a bit better at staying on at higher pressures but were more flat prone. Any tricks to getting the tire to stay put? Classic content are the rims and the bike, a '73 Jack Taylor curved tube tandem.
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\r?\n>Thanks!
\r?\n>Paul Raley
\r?\n>Nice riding weather in Leonardtown MD
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