Finding the correct Inner Tube

[Steve_j]

Hi all,

If any novices like myself are having trouble trying to find the correct size inner tube, then take a look at this Video tutorial http://www.totalinnertubes.com/tutorials/What_Size_Inner_Tube.html I found it very useful in finding the right one.

 

[Paulus]

What size are you trying to find?

 

[Chris S]

Is the correct size all that important?


I've got an MTB inner tube in a 26 x 1 3/8 tyre (I had to stretch it over the rim to get it on!) I've done about 30 miles without problem so far.

 

[Brommyboy]

The rim size is the important factor. Any 26"x decimal number is a different rim size from 26"x fractional number. The former is 559 mm and the latter 590 mm. 700C has a rim size of 622 mm. If too small then the inner can be stretched but it will be thinner as a result; if larger then there will be a fold within the tyre which can form a bulge and even chafe. The second measurement is the width of the tyre/tube. A narrow one within a wider tyre will be very thinly stretched within the tyre and liable to explode inside the tyre if punctured, becoming irrepairable.

 

[Arch]

Is the correct size all that important?


I've got an MTB inner tube in a 26 x 1 3/8 tyre (I had to stretch it over the rim to get it on!) I've done about 30 miles without problem so far.

There was a thread over on YACF a while back, about someone who stopped to help a pair of cyclists on MTBs, who had a puncture and no tube. He offered a spare, not the exact right size (I think it was 700c, not 26"), but would get them home he assured them, and they point blank refused it because they said it wouldn't fit, preferring to wait for the taxi they'd called.

As for finding the right tube, I note down the number on the tyre, and find a box with the same numbers in it, or a range that contains the numbers. I didn't realise it was hard...!

 

[Chris S]

Putting a 559 mm inner tube on to a 590 mm rim will stretch it by about 5%.

I don't think this will seriously weaken the rubber - you can blow up an inner tube to about 300% of its original size before it explodes.