I have built up a collection of tires here and inspired by a thread in the fat bike forum I decided to mount, inflate and measure them all. It could help us all if you did the same and also post your results so we know the true widths of tires on the wider rims we use for unicycling.
Please indicate the width of rim you are measuring on as well as the amount of use the tire has had as they tend to stretch over time.
measurements are casing/tread or casing only if it is the widest part of the tire.
Schwalbe Racing Ralph 2.4 (new) = 2.48
Intense System 29 (new) = 2.36
WTB Prowler SL (50km use) = 2.32
and some measurements from the thread that inspired this
also on a Uma 50mm wide rim at 20 PSI
The biggest surprise for me was the size difference between the Duro and the Gazz. I knew the Gazz was bigger but did not think the difference would be a full half inch at the casing. It is now also clear why some frames “have clearance for 3” tires but not a Gazz."
I have a 26" hookworm at home that I would like mount and measure if I have the time.
Keep in mind that the widths you quoted are the static widths. That means that if you take a tire and put the calipers over it you would measure those widths. I actually asked the owner of Arrow Racing about this. He told me that with the Arrow Wide Bite 24X3 the contact of the tire on the ground when being ridden would be 3" even though the static width is only 2.75. That is because the tire gets “squashed” down with the rider’s weight. Now with a Nokian where the profile is very flat the static and footprint width will be pretty similair whereas on a rounder Duro the squishing effect is going to cause more rubber to contact with the ground.
I am assuming that the footprint widht is even going to be wider with unicyclists than with bikers becasue we tend to run lower tire pressures and our weight is not dispersed over two tires!
Good point Unicorn, it would be interesting to mount all the tires ride, over a bit of clay mud and then measure the width of the track, but that would be more work and you are adding a whole lot more variables so I don’t think that number would be as useful. Also this might help if someone wants to see if a tire will fit in their frame (my Gazz does not fit in a KH frame but the Duro has plenty of room.)
Static casing width is also a pretty good indicator of tire volume.
So… nobody else wants to measure their tires to add to the knowledge of all unikind? You don’t need a fancy caliper, just a carpenters square with a block of wood would do. More numbers gives a better idea of what is normal for a specific tire. I have a feeling my Gazz is stretched out more than most as I have seen others using them in KH frames.
Nokian Gazzaloddi 24x3.0 to be ~2.9’’ (only like 10km of use so far).
This was a pritty in-accurate measure though. Its on a Nimbus muni rim (which is either 40mm or 42mm, I have read these different widths from UDC). It fits in my KH frame fine with about 4mm clearance on the sides.
A few more points about static width, footprint width and volume:
Keep in mind that the "squishing efect only happens where the tire touches the ground.
the footprint width will vary depending upon the hardness of the ground. You will have a much wider foodprint on rock than on mud or sand.
Some tires have a taller profile. These tires could have more volume volume than tires with a fatter static width.
Borderline tire fits in the frame could be a factor of how much air pressure you ride the tire with and or how weared down the edge knobs are. I know that the edge tire knobs of the Gazz and the Arrow wide bite angle out differently depending upon the air pressure. This could be the decidiing factor deternining if a Gazz can or can’t fit in a frame.
The heavier the rider the wider the footprint is going to be in relation to the static width.
The lower the air pressure the wider the footprint is going to be in relation to the static width.
By the way the Arrow Wide Bite has a static widht of 2.75 just like the Duro.
It does have a more square profile. I like to think of it as a cross between Duro and the Gazz!
Depends what you mean by “wide” rims. I’ve got a Racing Ralph 2.4 on a standard KH29 xc rim and a Duro on a new Nimbus 26" rim. I’ll measure them if you’re interested - but they’re not on massive rims by unicycle standards.
Duro Leopard 3" (about half worn in the middle, but not affecting the outer knobs), on a 2009 Nimbus 26" muni rim, 18-20psi. 2.75" carcass, 2.95" tread.
Schwalbe Racing Ralph 2.4" on 2009/10 KH29 xc rim (the one without the holes, not the freeride rim), ghetto tubeless, 25psi. 2.4" exactly at the carcass. Tread is a tad narrower.
Rob
EDIT: Weird that my Duro seems to be slightly wider than Eric’s even though it’s on a narrower rim (I couldn’t find the Nimbus muni rim width on UDC but I’m sure it’s not as big as 46mm). I did my measurements by putting a big adjustable spanner across the tyre then measuring the gap with a ruler, so it should be reasonably accurate.
I am not suprised that your Duro is wider than mine even though it is on a skinnier rim but I am surprised by how much bigger. If I remember right the Nimbus rim is 42mm wide so only 6mm skinnier than mine. I am also pretty sure that the KH29 XC rim is 38mm wide.
the more you ride a tire and the higher pressure you ride it with the more it will stretch. I studded my Duro right from the get go so only use it on rides that I expect to hit lots of ice. It does not have that much use and is usually run with really low pressures so it probably hasn’t stretched much at all.
I noticed in my first post I first said that the Uma is 59mm wide then I say 50mm later in the post. 59 is a typo (should be 50).
Yes, I was quite surprised by the nearly 1/4" difference. I suppose some of it could be down to stretching, but I don’t run mine at high pressure (never over 20psi). It is a good 18 months to 2 years old though, and gets ridden mostly on very rocky trails so it’s had a good pounding - might be enough to loosen the carcass up a bit, although I’d expect the rubber to show some cracking if it had stretched that much. Some of it could be manufacturing differences - I’d imagine there’s more than one mold. And some of it will be our measuring, although it sounds like both of us were reasonably careful to get a true figure.
I’m surprised that both the tyres I measured are so close to their claimed sizes (in fact the Ralph is spot on), when I thought tyre manufacturers tended to over-state the widths of bike tyres. Perhaps they secretly spec them for typical unicycle rims and don’t want to admit it to the bike world
I wonder what the difference between tube and tubules. I also had an idea to get more consistent tire readings. For mountain tires a standard 20 psi, and road tires at 55 psi.
