Tyre won't sit symmetrically in rim

[alexb]

One of my colleagues has brought a bike in with a rear tyre that will not sit symmetrically in the rim.
It's a Continental GP5000 (700x25c), so not a cheap tyre.

The wheel looks fine, it's round and true.

I took the tyre off twice and I can't get the bead to sit evenly.
Rotating it to a different position in the rim and I get the same problem, in a different part of the wheel.
It also looks like the tyre is sitting low in a different part of the wheel, so it doesn't seem to be consistent.

Any ideas?
Inner tube is a Continental Race 28, so also not rubbish.

[Brucey]

Contis can be a tight fit and the result is often that the tyre sits low at one point, initially.  It is quite possible that the rim is above spec and the tyre is a bit smaller than spec.  Sometimes the thickness of the rim tape (if it goes over the full width of the rim well) makes enough difference that it causes the tyre not to seat properly.  Other times the tyre will only seat correctly if it is overinflated.

A while back I fitted a new conti for a friend; the tyre would only seat properly if inflated to over 120psi and as soon as the pressure dropped below 90psi it unseated itself again. That was on a rim that I would describe as 'easy' for tyre fit.

So I'd suggest looking carefully at the rim tape and if that looks OK, I'd try inflating to a higher pressure than normal, with talc in there as a lubricant.

cheers

[Kim]

If it's happening at the same place on the tyre, it might be a manufacturing defect.

I've been playing this game with 28-559 Schwalbe Pro Ones on various rims without success.  As Brucey suggests, overinflation, lubrication and experimenting with different rim tape can help.

[Paul]

Have you got a different wheel to try it on, for the sake of comparison?