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What size of inner tube fits a 650x47b tire?

It's gravel bike. The tire states it's tubeless ready but there's a tube in it currently.

2 Answers 2

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650B tyres are another way of saying 27.5" or 584mm

The modern ETRTO standards for measuring tyres would call this a 584-47 or perhaps 47-584.

So any tube that is for a 584mm tyre, and covers a width that encompasses 47mm will be fine. Do remember to get the right valve type for your rims, likely Schrader / A/V / car style though Presta are also fairly common in this size.

Here's an example of the markings on a tube that would suit you (check valve though)

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In addition to Criggie's answer, I would suggest trying to oversize your inner tubes. It may be slightly heavier than the tube that is "compatible" with your tire, but if minimal weight gain isn't an issue then there are benefits.

Most grabfood or similar delivery bicycle riders in my area do so as they surmise that upsizing results in a tube that is much closer to the size of the tire in its unstretched, uninflated state, resulting in better puncture resistance. I can also anecdotally support this.

A good rule of thumb is to upsize your tube 1.25 times the printed size of the tire. So with 650x47b, look for an inner tube whose smallest to median size in its size range is more than 650x55b but less than 650x60b.

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  • I've heard the exact opposite, i.e. smaller tubes being stretched out would hold up better. My suggestion would be: ride the correct tubes, pressure and tires for your riding. And: Be prepared to have a puncture!
    – DoNuT
    Commented Sep 30, 2023 at 13:19

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