trial rim size?

just a question about the rim/tire size on trials…

they’re advertized on UDC as a 20" trials, but then it says the rim/tire size is 19"?

most say they come with a maxxis creepy crawler 19x2.5

but on they only offer the creepy crawler in a 20x2.5

so which is it?

20" or 19"?



the size of the wheel is measured by the outside of the tire for some weird reason. the mod bike “trials” wheels use a slightly smaller rim which is still called a 20" because of the massive tire used. the technical size is 20 but most people call it a 19 so you won’t be confused as to why you can’t get your bmx tire on it.


basically, you couldnt put a creepy crawler on a 20" rim, or a 20" tire on a 19" rim?


Yeah…Any tire that says 20x2.5 will most likely only fit a 19" rim and regular tires wont fit the 19" rim

i was wondering about that… just kind of weird…

Yeah it’s a pain, especially as tyres like the Onza sticky fingers come in both 20" and 19" sizes.

As far as i understand it, when they started making huge tyres they would no longer fit in BMX frames, and they didnt want to change the frames because they were exspensive, so they invented slightly smaller rims to allow huge tyres to be used without the outside diametre much exceeding that of a normal 20".