Tyre does not catch rim after replacing inner tube

[rliu]

I changed inner tubes last night for 700c 28 tyres with 27 1 1/4 tube, which I believe are basically the same with different metric and imperial measurements. However after swapping I have noticed that the tyre isn't catching the outter rim. Is this just because there needs to be more inflation? I was using a hand pump and stopped when I felt the tyre was relatively full and there started to be more resistance when pumping. Is it easy to burst inner tubes from too much pumping? I tried to ride it once and the tyre went flat almost immediately and lost a lot of pressure.

 

[Canrider]

http://sheldonbrown.com/tire-sizing.html

I wouldn't expect an Imperial tube to work with a metric tyre, although I can see why you tried. The link above (as I read it) suggests that a 27" tyre is 630mm where a 700C tyre is 622. Is that 8mm in the tube enough to pop the tyre off the rim? Maybe.

We need more information here, I think. What kind of bike are we dealing with? Does it have 700c wheels? If you're trying to put a 700c tyre on a 27" wheel it definitely won't fit properly (although it'll be too tight, not too loose).

 

[tyred]

I doubt the size of the tube is anything to do with it as the difference is marginal and these sizes can be considered interchangeable. The tyre isn't seated properly. Let it down again, push the valve back into the tyre to make sure the reinforced bit around the valve isn't getting in the way and try and centre the tyre. It should have a "witness" line around the beading to help to seat it centrally on the rim. Due to manufacturing tolerances, some rim/tyre combinations can be tricky to get right.

 

[Chris S]

I had a similar problem - I'd made the mistake of screwing down the nut on the valve (on older inner tubes it holds it firmly to the rim) before I inflated it.

 

[Paulus]

I doubt the size of the tube is anything to do with it as the difference is marginal and these sizes can be considered interchangeable. The tyre isn't seated properly. Let it down again, push the valve back into the tyre to make sure the reinforced bit around the valve isn't getting in the way and try and centre the tyre. It should have a "witness" line around the beading to help to seat it centrally on the rim. Due to manufacturing tolerances, some rim/tyre combinations can be tricky to get right.

Seconded.