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I inherited an older road bike from my sister that I wanted to fix up for my daughter. The tires and inner tubes needed to be replaced.

The existing inner tubes were old and faded, but I could read a 700 x 35/43C on them. I went to Wal-Mart and bought new tires and inner tubes. The 700x35/43C tires fit just fine, but the inner tubes looked to be noticeably too large, like a few extra inches too much to fit into the tire.

  1. Is it possible that the inner tube was defective in some way?
  2. Is it okay for the inner tube to have that much extra material? It seemed to me like it would have to pinch or not be fully inflated to fit?
  3. Should I try a slightly smaller inner tube?
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    What was written on the box for the tubes?
    – Criggie ♦
    Sep 27, 2021 at 2:51
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    The tubes were 700 x 35/43c Presta valve.
    – Paul
    Sep 28, 2021 at 3:46
  • fair enough - it was a little confusing that your tyre says 35/43C because normally a tyre has a single width, not a range. Tubes on the other hand always have a range, frequently 18-25, 25-35, and 35-4something.
    – Criggie ♦
    Sep 28, 2021 at 6:36

1 Answer 1

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This happens sometimes and I don't have an explanation for it. It is not a sign that you bought the wrong thing. Sometimes the tube just seems like it has extra diameter, even when it's inflated only enough to give it shape.

You want the tube to be in the tire without being folded over or bunched up. Those conditions can create stress risers that lead to failure, and in some cases also cause weird bulges in the tire. Usually what I do when I'm fighting against this concern is do my best to cram the tube in as evenly as I can, inflate the tire, deflate it, maybe go through a few cycles of that, then deflate it again and pull the tire to the side without unseating it to check how evenly distributed the tube is. Usually it works itself out doing this. Talcum powder is a way of encouraging it to work itself out that could be useful in extreme situations. You can either shake it into the tire all around or put some in a baggy, put the tube in, and shake it to coat. I've known some mechanics who always do this because it only takes a second and makes the tube more cooperative to install, but I don't bother.

Don't get smaller tubes to address this, just stay with tubes that have a nominal size that matches your tire. This is just a quirk of some tubes. If you just can't get it installed without a folded or bunched up section, try a different brand.

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  • I'll try again with the tubes. I don't see how they would fit without bunching up. If necessary, I'll post a couple pictures. Incidentally, the rim diameter (measured outside edge to outside edge) is 25" ...
    – Paul
    Sep 28, 2021 at 3:47
  • If it's really impossible to keep it from bunching, do the talcum powder thing (baby powder works), let it be bunched, inflate it, and see if it sorts itself out.
    – Nathan Knutson
    Sep 28, 2021 at 4:37

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