Coker tire (tyre) pressure

I started to pump up my Coker tire (tyre) yesterday when I realized (realised) that I had already gone over the stated limit of 32 psi (2.25 bar).

Then I thought back to when I first got my Coker… Didn’t I used to inflate it to about 55 psi (3.5 bar)? Given my weight of about 190 lbs (about 13.5 stone), what’s the maximum psi that I could safely inflate that sucker to?



David 14 lbs (Stone)

55 psi?
Can I put that much pressure on my stock Coker tire?
I am afraid I would burst the tire if I put that much pressure.
With about 40 psi I ride comfortably on my new Coker, it seems to handle the bumps, small pebbles well.

By the way, where do you guys get your tubes if it tears?
Are Coker tires more/less prone to puncture by thorns, glasses?

Go tubeless and you can run really low pressures and it will still roll better :stuck_out_tongue:

But even a tubed Coker is fairly puncture proof- in fact, I have never seen anyone puncture one (must be the 2kg’s of 4ply rubber), and the 500g inner tube. If you need a Coker tube I think they’re about $25 for from memory, otherwise stick a 29’er tube in it for half that.

I usually vary my pressure depending on the terrain. From 27.5(off road) to 45 PSI(road). Never had a problem. Take advantage of the awsome ability to vary the pressure of the coker tyre without a problem.
Have Fun.

Adam Cohen
Just One Wheel Inc.

I weigh the same as you or a bit more. I usually pump my tire up to 60 psig and let it slowly drift down to 40 psig over several months. I once loaned it to Nathan for a race and he pumped it up to 80 psig. I left it and didn’t pump it up for a year. This was all stock rim, frame, tube, tire.

Like Ken said, I think they are virtually puncture proof. I have had three tires. Number three is brand new and awaits a new wheel. Number one I wore all of the tread off of so it is essentially a racing slick. Number two I wore all the tread off of and the core started to show through all the way around. I just went back to number one fearing that number two would burst the core. I’m saving number three for the new wheel.

I have only used the original Coker tube. It is unpatched and I’ve had it for about four or five years. My seat tube has punctured twice, though.

I’ve never punctured a Coker tire and also haven’t heard of anyone suffering a sudden blowout or even a slow leak. My Cokers have only ever had the usual slow loss of pressure over weeks and weeks. And in my city riding, I have to go thru glass all the time (welcome to Brooklyn). So I’m not worried about a puncture. What I’m worried about is an explosion due to over-pumping the tire. I’d love to take it to 60psi, but I REALLY don’t want to have a Coker tire explode on me. I’ve had it happen with my 29" uni and twice with a smaller wheel, and it’s bad enough at those speeds, but if I am riding downhill thru the park and the tire suddenly burst, I’m in real trouble.

I’ll try it at 60psi, and I’ll get some nice platform pedals, too (as per the other thread). And I hereby bequeath my unicycle stuff to my kids in the event…

So the answer to ‘how much pressure can you put in there’ really boils down to how well-seated the tire is on the rim. Also in extreme situations, I suppose the condition of the wheel in terms of spoke tightness could be a factor as well. The important thing to do is make sure your tire is well-seated all the way around before cranking up the pressure. I don’t know the number, but I run mine fairly hard as well.

It’s the original tire and tube from 2002, where it was the “demo Coker” at NAUCC and Unicon 11. The tread is wearing off the tire, but the fact that I’m still on the original is mostly a factor of me not putting enough miles on it…

If you’re going to pump it up to 60 psig for the first time and are worried that it’s going to burst, wear hearing protection. There is alot of energy stored in that tire at that pressure. A little 700cx25 tire bursting at about 100 psig is like a pistol round. In an enclosed area, that’s going to REALLY hurt your ears. I know this from experience. Anyone who’s blown a tire like that will tell you the same thing. Mine blew in a basement.

Why would you want to pump it to 60PSI? :astonished: That sounds painful to ride on.

On my first ride out on my Coker with joemarshall the other week Joe got a puncture. Although we could hear the air coming out of the tube we needed the assistance of a nearby river to locate the hole. I think Joe runs his tyre quite high whereas I being new to Coker’s have it at exactly 32psi, but what was the puncture culprit? Glass.

I noted it’s not the first patch on Joe’s tube though he does put in significantly more miles than most.

EDIT: I must proof read before hitting send.

I don’t know about where you ride in NZ (and I want to talk with you about NZ…), but I have a lot of start/stop riding (traffic lights, mostly). I like to circus idle, and the more air the better – it makes swiveling much easier. I also rarely go up curbs, so again I don’t worry much on that score. And I like the responsiveness of a tight tire. I ride my 20" freestyle at 85-100 psi!

I use a foam seat for my Coker and never have saddle soreness – I liked my air seat better, but it kept getting flats.


Re: Coker tire (tyre) pressure

Dear 14 Stone: The official answer is 32 psi.

Unofficially, I run mine at 60 psi on the road. Rolling resistance is much less at that pressure. Cracks develop in the sidewall but don’t seem to affect the performance or safety at all.

I have had one up to 85 psi for half an hour. Don’t try this at home, or if you do wear ear, eye, nose, throat, and liver protection.

At the first Unithon I attended, you convinced me to raise my pressure from 32 psi to 55 or so. I was glad I did.

Off-road, of course, is a different story; using a MUni-like pressure (guess: about 15 psi?) helps, especially in the snow and ice.

2Many Stone

Is there a trick to getting the bead of the tire seated properly on the airfoil rim? Will pumping more air into the tube fix this? Currently, sections of the bead of my Coker tire are near the bottom of the “V” groove in the airfoil rim.

Generally, putting in about 60 psi and waiting will take care of that, then drop to your preferred riding pressure. Wear hearing and eye protection!

Another technique which I just discovered a few weeks ago is to locate the spot where the tire is low and lean that spot against a wall. Press sideways on the wheel to help the tire roll out a bit into proper position. This technique works much better than beating on the tire with a rubber mallet. :frowning:

Caveat: this explanation is not intended to provide complete installation instructions.

Thanks Dave, I’ll try that.

In my dad’s bicycle shop years ago we kept a lite soap solution handy in a squirt bottle. When we had a tire where the bead would not seat correctly we’d deflate the tube and spray the soap between the tire and the rim. We’d then inflate the tube slowly and the tire would usually seat itself. This procedure worked really well with the larger width moped tires which were a bear to get on the rim.

Be careful with this because if you use a compressor and blast the air in too quickly you risk blowing the tire off the rim which can ruin the tire.

Pump up the tire to about 60 pounds and just wait 30 minutes or an hour or so. The Coker tire will sometimes gradually slide its way into place.

You can lubricate the tire bead with silicone spray lubricant before installing the tire. The silicone spray will help the tire bead slide into place easier when it is first inflated to 60 pounds or so. Or you can use the soapy water suggestion but I don’t like getting moisture in the rim because the moisture can be bad for the rim strip and could cause some corrosion in the rim. Silicone spray lubricant is better.

Since you’ve already got the tire on the rim you could deflate the tire all the way and then spray a towel with silicone spray or dip the towel in soapy water and rub it on the bead of the tire. Then you can pump it up and see if it seats easier.

Sometimes it may take a couple cycles of inflate to 60 pounds, wait 30 minutes, deflate, then inflate to 60 pounds again before the tire will seat properly.

Thanks for everyone’s suggestions. I got the Coker tire seated properly without a hassle. It was easy, I pumped it to about 40 PSI and watched as the bead slowly emerged from inside the rim and seated itself properly. This took about 1 minute and was without the use of lubricants of any kind.