Problems with putting tyre back on

[Iainj837]

I have just fixed a puncture, the problems is as I'm putting tyre back on I can't get the tyre to sit properly on the rim, when I pump the tyre up it starts to push the tyre off the rim on both sides.
How do I get it to sit correctly ?

 

[Mr Phoebus]

When the tyre had the p*nct*re did you push/ride the bike home/to work, etc with the tyre deflated?
I ask this because with some tyres that can stretch/bugger up the bead
and make the tyre unusable again on that particular rim.

Just a thought about your predicament, but it may not be the case.

 

[Mr Phoebus]

Also, is the tyre new or really getting on a bit?
Have you checked for perishing, any bead showing through the rubber?

 

[RedBike]

If the tyre is popping off the rim like this then the bike is highly dangerous. The tyre could pop off the rim at any time. To er on the side of caution I get it looked at by a bike shop.

I seriously doubt you've damaged either the rim or the tyre riding it flat. However, as both can be easily damaged in this situation it certainly doesn't hurt to check. You should be easily able to spot this sort of damage. If you can't see anything obvious then there probably isn't any damage.

 

[jimboalee]

Raleigh Man might be riding an old pair of single skin alloy rims, such as Rigida, a favourite of Raleigh. Over time, the rims plastically deform with the spoke tension, reduce in diameter and tyre seating becomes a bit dodgy.

Measure the seating diameter and compare it with the 622mm for 700C, or 635 if it’s a classic.

 

[peanut]

Over time, the rims plastically deform with the spoke tension, reduce in diameter and tyre seating becomes a bit dodgy.

we love it when ya talk dirty Jimbo

Only other thing I can think of is if the rim tape is that orrible thick rigid grey plastic stuff. If it isn't centrally placed It can cause the tyre bead to fail to seat on the rim properly.

What size inner tube are you using Iain ? and what size tyres are you fitting ?

 

[Iainj837]

I think the wheel has had it, so I am going to replace the wheel, I have had the bike between 2 to 3 years so the tyres need replacing, I have done about 2'600 miles and they are the original tyres when I bought the bike.
In fact I think I will have a full service done.
so an early christmas for my bike

the wheels are alex rims DH 19 622x18

 

[Iainj837]

tyre size 700c x 28 not sure about inner-tube

 

[peanut]

I was just wondering if you have the correct size tube ? if the tube is intended for larger hybrid/mtb rims it may have too much bulk and will prevent the tyre beads from engaging in the side of the rims. (It will have the size written on the tube.)
Have you tried partly inflating the tyre then bouncing the tyre on a hard surface ? also I usually go round the tyre and press it away from the rims on both sides with my thumbs. This checks that the tube is not trapped under the tyre bead and should help the tyre beads to sit into the rims.

I think what is happening is part of the tube is becoming trapped under the tyre bead and is pressing the tyre off the rim before it gets a chance to engage with the rim lip

 

[jimboalee]

That's a bloody wide tyre for a 18mm rim.

Is that 18mm across the seats or 18mm across the brake tracks?

 

[Iainj837]

It may well be the inner-tube, like I said it's the oringinal wheel and tyre from the bike being new or the wheel.
I am just wondering I had an accident last year the forks were changed. Would that make a differance, but having said that I rode it for a while once it was fixed

 

[peanut]

no I am sure it is the tube getting trapped under the tyre bead. Bet you a new tube

 

[jimboalee]

In 'The Bicycle Wheel' by Jobst Brandt, ( I'll check when home ), he has a diagram of the forces a tyre exerts on the rim. The inner tube width makes no difference. If the tyre is too large, it will want to roll off the clincher.
It's reasonably OK on an MTB where the inflation pressure is less than 60 psi, but on a road bike where 100 psi + is pumped in, the tyre could very well be lifted off the seat.

 

[mickle]

My guess is that you have a kinked bead. New tyre time unless you can manually manipulate it back to it's original shape.

 

[jimboalee]

+1, new tyre time. Ask the LBS chief spanner which is the best size tyre for that rim.