I have a 2016 Mongoose Brawler that I am fixing, among the things that need to be replaced, the rims are one of them. I have 16" tires, so what size rims will fit those tires? And then what spokes size will I need to fit the rims?

  • 2
    I don't know but your bike as described SHOULD have 20" wheels, like most BMXs. Please would you find some numbers on the tyre and we'll go from there.
    – Noise
    Jun 23 at 12:49
  • thanks, I'll do that.
    – user65550
    Jun 23 at 18:55
  • Be lazy - if you have the old rim, and it fits existing spokes, then the replacement rim would have exactly the same dimensions and therefore suit the existing spokes. What's the damage that means the rims need replacing ?
    – Criggie
    Jul 27 at 19:29

2 Answers 2


If you are not an experienced mechanic and if you don't have wheelbuilding tools, this is something that's probably best left to the folks at your bike store. They will have the tools to measure the effective rim diameter (ERD) and the relevant hub parameters (i.e. center of hub to center of each flange, noting that this is symmetrical in front and asymmetric in the rear, and the flange diameters).

Often, rim manufacturers publish ERDs on their websites, or the ERDs may be floating around in Excel files for wheelbuilders. The same is true for hub measurements. My understanding is that mechanics will still prefer to measure those parameters themselves, because there may be some ambiguity in how people define each measure, or the rim or hub model wasn't in the database or it received a running manufacturing change. I was under the impression that ordering spokes 1-2mm too long (but not too short) is still acceptable for a wheel build, so there could be some room for error in the measurements if you're taking them yourself.

If you are determined to take the measurements yourself, I'd consult this Park Tool page. It should either give you what you need or convince you to outsource the task to someone with experience. If you are determined to build the wheels yourself, you could consider if you can pay a mechanic at the bike store to measure your hubs, select a rim, and order spokes for you.


For the spoke sizes you should have the hub dimension and rim ERD cross pattern first to determine the spoke length.

  • 2
    Hi, welcome to bicycles. This has probably attracted a down-vote because it mentions some of the basic points without giving enough information for people to know how, or what to do with the information assuming they figure it out.
    – DavidW
    Jun 27 at 20:19

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