Alright so I’m confused on wheel sizes on a BMX.

I just bought a BMX frame and it came with the front forks and wheel and tire, but it needs a rear wheel and tire.

The tire on the front is 20inches tall so what size wheels do I get?

Do I get 20 inch wheels or what? I’m confused.

  • What else is missing? Just the rear wheel? Check that it has two brakes with pads, a chain, a chainring, cranks, pedals, seatpost and saddle, etc. Adding a single clear photo of your new bike to the question could help a lot.
    – Criggie
    Mar 7, 2020 at 7:39
  • Also, please read the sidewall of the front tyre. Its got a two-part number that looks like xx-406 or 406-xx This is to check that it is indeed a 20 inch wheel.
    – Criggie
    Mar 7, 2020 at 7:41
  • Just saying that it surely is a strange way to sell a bicycle. Could be that the rear wheel is still chained to some lamp-post. :-/
    – Carel
    Mar 9, 2020 at 20:45

1 Answer 1


You need a 20" wheel, tire, and rim strip. You'll probably have some options for what width of tire to get. They start at around 1.95" wide. Most actual BMX frames can take at least a 2.1" in back. There's a degree of preference there. The rim won't care for the most part.

You need to select a rear cog size that both matches the chain length if you're planning on re-using it and/or is a functional combination with your chainwheel size. All the BMX parts sites like Dan's and Albes have extensive guides on this, and there's a question or two about it on here as well.

If you wind up needing a freewheel or cassette cog then you'll likely be buying it separate from the wheel. If you need a one-piece driver (8, 9 or 10 teeth) than typically one selects a wheel that comes with the size you want pre-installed.

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