Which tube will fit a -(700 x 25c) wheel? BF got a fancy new bike, and promptly punctured the inner tube, I’ve been looking in shops for the right size and getting in a right faff trying to find the right size.

His wheel says on it -(700 x 25c)

I know it’s a Presta Valve, and has to be 700, but I’m confused on the 25.

Does the inner tube have to be 700x25c, or would a 700 x 18-23c fit?

There’s a 700 x 35-38c which I’m sure is way too big, but I’m also concerned that the 18-23c is too small?

Does the inner tube specs have to end in 25? Or include 25 in the numbers? Like say 18-28 would? (Just random numbers)

Many thanks for any help
The marking on the tire '700 x 25c' means a 622mm diameter rim, with a nominally 25mm wide tire. ('700c' comes from an older French standard for wheel and tire sizes, it's very commonly used to refer to the standard road bike rims and tire size).

Inner tubes fit a range of tire sizes as they are quite flexible. The two numbers denote the min and max tire sizes. A 700 19-25c tube will fit, as will a 700 25-28c. As long as you tire size fit in the range specified you are good.

Note that tires and tubes may also be marked with 'ISO 622' or 'ETRTO 622' These are both equivalent to 700c.

You also need to get a tube with the correct valve stem length. Tubes come with a range of valve lengths to fit different depth rims. The length is not usually marked on the tube but is easy to measure.

The simplest thing to do of course is take the punctured tube to a bike store and simply ask for new tube that is compatible, for a 25mm tire. Or get your BF to buy his own tubes (or learn how to patch them).