I’m about to go on a short vacation and I was going to replace the Ritchey WCS 700×35 tires I have used so far (tubeless) on a pair of ZTR Grail rims.

The replacements I’ve bought are Challenge Paris-Roubaix 700x27c; my intention was to run them tubeless as well, given the experience with the Ritcheys (non-tubeless tires, ran just fine). The first tire blew off the rim at about 60 psi, both before and after(!) adding Stans (second time it was in the shower booth, thankfully). The rims are rated to 100psi for 28mm (so they should hold a 27 just fine), the tires say 90minimum, so 60 is way too low.
After reading around on the internet and on the manufacturer’s website, I decided to try the second brand new tire with a tube on the same rim, with exactly the same result.

Is there something wrong with these rims when used with ‘normal’ road tires, or are these particular tires not fit for them?

Those rim pressures (the one’s printed on the side) are for use with Tubes, not tubeless.

I’ve found that Stans rims are pretty poor for narrow tyres on wideish rims when ran tubeless. I’ve had several tyres leave the the rims (Crest and Arch) when the tyres get close to the max recommended.

That’s what I read as well, but I saw no difference when I tried to use a tube – the tire left the rim and the tube blew at around 60psi.
Also, the table on the rim starting at 23mm got me thinking this should work, but given your experience it would seem that is not always the case.

That’s what I read as well, but I saw no difference when I tried to use a tube – the tire left the rim and the tube blew at around 60psi.

It’s likely that the bead got damaged when it blew off when trying to use tubeless.

edit: read the post fully and see you tried the 2nd tyre with only a tube. Pass. They should be fine with tubes.

That’s why I used the second, brand new tire… Now I have two possibly damaged tires. On a visual inspection they seem fine, though.

l.e. Yes, I was hoping it would be fine with a tube as well. Now I’ve fitted the Ritchey back and I’ll just use CX tyres on the long-ish tarmac rides that I have in plan.

Is there not an issue with challenges blowing off the rim, quite a few reports and my Strada biancas did it in the workshop at 90psi

The replacements I’ve bought are Challenge Paris-Roubaix 700x27c;

They’re not meant to be run tubeless AFAIK, the bead isn’t strong enough.

edit: read the post fully and see you tried the 2nd tyre with only a tube. Pass. They should be fine with tubes.

I had a problem with a GP 4 season blowing off a Grail rim, that was with a tube. They do need to be fitted very carefully, with the bead properly worked into the well, and you should hear a pronounced “crack” as they inflate.

I’ve had the exact same problem with Challenge tyres, I think they were Strada’s. Both the front and rear running tubes at 100psi kept blowing off, I swapped between different wheels (Mavic, Stans) and could never get them to stay on the rims. Bit scary when you’re riding along at 25mph and it lets go on the front.

Bit scary when you’re riding along at 25mph and it lets go on the front.

One of my biggest fears when heading down a hill at 50mph is this…

A friend just tested the tyres on some of his wheels (Campagnolo, DT Swiss) and they seem to hold at 110psi.

I’ll stick to tubeless-rated tyres on the Grails for the future.

Bearing in mind that they are not designed as tubeless and have a different construction to many tyres being open tubulars with a minimal bead, I think you may be on a hiding to nothing there. It would be nice if these tyres would run tubeless. I have had some Strada Biancas for about 2 years and they would be great tubeless on my Pacenti CL25 rims.
If anyone does get this to work please say how.