Tire Sizes for KH 20

From what I know all the 20" Trials unicycles are actually 19" rimmed. The description however is 20". This holds true for the tires also. For example the Maxxis Creepy Crawler is described as a 20X2.5 inch tire. Is this the same size tire that would fit on a BMX bike? I just got a KH 20 and just assumed that I could use any decent BMX tire on it. Is this the case or do I have to get special 19" tires?


Where does the 19" come from?

Measuring my KH 20 installed tire diameter, I get 20.5". A Rim Diameter of 15.5"
My guess is they call it 19" because it uses a fatter tire from the “mod 20 inch” size trials bike, which is different then a regular 20" bike tire. Reading the sidewall of my maxxis creepy tire on the KH20 it says 67-387 (20x2.5).
So where do they get 19 inch from?
I guess, the point is to make sure you are buying a “trials " tire.
I just taped the tire and rim of my cheapo regular 20” uni. It has rim diameter of 16 3/4" and a tire installed diameter of 19 3/4". It’s tire says 50-406 (20x 1.95). So strange. Both tires are marked 20xsomething, yet the trials rim is 1 1/4" smaller diameter.

i dont know where they get the measurements from… but a bmx tire will NOT fit on a trials rim.

the 20" is referring to the outside diameter of the tire. It needs mod tire, you can def not put a 20" BMX tire on it.

Think of it as frame size. Its a 20" frame, you could install a 20" bmx style wheelset on that frame.

It’s called a 19" because it’s a little smaller than a 20" rim. However this isn’t used in the bike fraternity as much, they use the word ‘mod’ to refer to 19" rims and tyres. The number refers to the OD of the tyre anyway, so calling both BMX and mod tyres 20" isn’t wrong, the whole reason mod rims came about was to get a fatter tyre but with the same OD as a BMX tyre, so it would still fit in the same frame, so they are intended to be approx. the same outer diamtre. I’m afriad it’s just one of those thigns you have to know if you want to ride trials.

Trials Tires

So then I would guess that any trials tire should fit. I would consider any 2 1/2 inch tire a trials tire. I don’t think that BMX bikes have anything bigger that 2.1 inch. Would this be a correct assumption?

I am a hardcore MUni rider but I am getting into trials because one I think that Trials skills will improve my MUni and two because I met a group of really nice kids who are great on Trials bikes and it is fun to ride with them. They however all have 26" weels on thier bikes. Is the 19" Trials tire a common tire? Or is it going to be hard to just walk into a bike shop and find one?

I hate that about the 24 tires. I can only order them through the online Unicycle vendors. It just pisses me off.


any 20(19)x2.5 trials will fit. On MOD bike there is a front and back, they are not teh same width (and sometimes tred pattern).

However you are wrong about bmx tires. 20x2.25 is pretty common, there are some new 2.35s out, and there is a 3inch slick bmx tire.

It is quite uncommon to walk into a bike shop and find a trials tire, let alone a MOD tire. Best luck is internet.

Someone can correct me here if I’m wrong, I think your only options are:

Maxxis - creepy crawler
Luna - Trials
Monty (I think there are a couple options)
Tryall - Sticky fingers (or something)

About half of my local bike shops stock mod tyres, you just need to find one that is geared towards your needs, my experince is that bike shops are either intended for commuters/road bikes or mountain/bmx/trials bikes. 26" is also popular for trials, although I’ve never worked out why.

That depends on where you live and how popular trials is. I have been into 10-12 bike shops in the last year, not a single one of them had any trials anything whatsoever. …yet

Trials bikes are much more popular in the UK

I looked into buying a trials bike in the USA. There are like 3 shops in the whole of the states! Their are no low end Monty, Onzas etc. here. Only 3 dealers online and the bikes start over 1000$ US.:frowning:
So the chance of walking into a bike shop here and finding a trials uni or bike tire is almost zero. You must order it online.

Well this is off topic, however when I measured my CC it was 3 inches wide :smiley:

Don’t forget the Monty tires, they have three or four.

i didn’t read 1/2 the posts or anything but the rim size is 15", not 15.5" (you measured it differently than manufacturers do) the outer diameter of the tire is different on every tire.
the way tires and rims are measured is that the average tire is about 2.0 … on a bike… the rim is always 4 inches smaller than the said size. so a 20" bike’s rim is going to be 16"… or close to it. it goes on, so on and so forth.

you definitely can not put a BMX tire on your rim. it is a mod rim, you can get a tire for around $30 and they normally last for several months. if you invest in a 15x2.5 motorcycle tire you won’t have to worry about the tire popping either.

there is no specific way to measure a tire.

i think onza has a trials tire
their are more than what you listed but the ones you listed are the only ones i have ever seen anyone ride

yes there is, the tyres are measured at a set psi, and the measurement is the carcase not the tread, so if you cut all the tread off it will be 2.5

also you my friens are wrong, 15" is way small, i measured my brand new kh rim (with no hub laced up) and it is 15 and 5/8" so either your rim is way small, or you measured way bad.

do not use a dirtbike tyre way too heavy and no bounce.

trials bikes have 2 different rim sizes, they have a regular sized 20" front rim and a mod, or 19" back rim, their front tyres are a touch thinner than the rear also.

at a bike shop you will need a bike trials rear tyre.
your choices are.
maxxis, creepy crawler
onza, sticky fingers
try all, sticky
monty, eagle claw (not sure if this is the 2.7 wide one?)

and i cant think of any others

a tyre should last ages, my luna is six months old and looks new

That makes no difference, the thread on a creepy crawler does not go round the tyre.

Thanks for all the Help

Thanks for all the help everyone. By being on the forum I know about Try All, Onza, Luna, Maxxis Creepy Crawler (Comes on the Stock KH20.) and Monty. I live in Israel and it is quite expensive to get things shipped here. I wanted to order just a KH seat cover from Municycle.com and they wanted 32 Euros just for shipping the 12 Euro Item! Therefore I am always trying to find common bicycle solutions for my unicycles. All the trials bicycalists here tend to ride 26" tires so no good. I thought that BMX might be a good solution but apparently not. Once again thatks for the help.