Tire Bump

[andyc]

Tire Bump?
Hi all!

I am having a problem with my tire. I get flats all the time and it is really unpleasant. I just got a new tire and new tube to try and fix this problem but now when I pump up the tire I get a bump and the tire jumps off the rim. I'm pretty sure everything is the right size.. I just don't know whats going on!

Any help would be great.

Thanks
Andy

[Bill]

Hi andyc,
I would like to say that your tire is not seated properly. Here is a post that addresses the same problem. http://forums.bikeride.com/thread-1084.html .

Part of it talks about truing a wheel but it goes on about tire seating. If you still have questions please do post here.

[cyclerUK]

Make sure that the inner tube is not too big. An oversize tube can force a tire off.

[Bill]

(07-16-2010, 04:53 PM)cyclerUK Wrote:  Make sure that the inner tube is not too big. An oversize tube can force a tire off.

Yes I forgot about that one too .

[trevgbb]

Many modern tyres, especially on MTB's and to a lesser extent, hybrids, are a very loose fit on the rim and it is important that you are careful to check the seating of the tyre on the rim while inflating.
1. fit the tube inside the tyre with just a little bit of air in it and go all round the rim making sure the tyre is seated within the rim, both sides.
2. if the valve body is threaded and comes with a nut, DO NOT fit this nut yet.
3. at the valve position, grip the tyre and push the valve up into the tyre, you should feel the tyre beads settle around the valve.
4 recheck all round, pushing on the tyre walls and feeling the tube within and making sure that the tube is not trapped between the beads and the rim.
5. start inflating, slowly, keeping an eye out for the tyre pushing off the rim. especially at the valve, if it does, push the valve up again to reseat the tyre.
6. when about half inflated, go all round the tyre, squeezing the walls together and pushing them down into the rim.
7, complete inflation, watching all the time for any bulges, in which case reduce pressure in the tyre and repeat from 4.
8. when you are satisfied all is ok, fit the nut if supplied.

and something else to look out for, make sure the rim tape is central and not too wide as this can stop the tyre bead seating properly.

This sounds quite a long winded process, but when you have done it a few times it becomes second nature and you should be able to change a tube in a few minutes at the most, and remember to check around the inside of your tyre for any thorns etc. that may be sticking through.