Coker tire sidewall cracking

I have a new coker tire and I was wondering if anybody has had any luck with any type of tire treatments to prevent the sidewalls from drying out and cracking. I think armor all is bad for tires but there are prouducts to protect tires sold at auto part stores and I was wondering if anybody has had succes with any.

Thanks, Dan.

Hi Dan, I’ve had three tires w/sidewall cracks. I was worried about it, but the tread wore out before I had any problems w/ the cracks. I would deflate the tire some between rides, don’t know if that helped or not. Besides that info, I don’t know of any products that you are looking for, although I did use Armour Alls “Tire Foam” on my motorhome tires and they look much better now. When will the snow end this year? Cheers.

“I think armor all is bad for tires but there are products to protect tires sold at auto part stores and I was wondering if anybody has had success with any.”

Armor All won’t hurt a tire and can keep rubber and vinyl pliable, but get it on the tread and you’ve got one slippery machine to control.
I’ve, also had some tires crack. Mainly stock, narrow tire due to low air pressure. The sidewalls take most of the weight of the uni. Sitting on a uni puts all the downward stress, or weight, on a 2"-3" section of the sidewall that is in contact with the ground. With correct tire pressure this stress is minimal, but with low air pressure the sidewalls have so much stress that they start to give - thus the cracks (this is especially true with thin-walled tires). Once these cracks form, they don’t go away, and can even be amplified by the correct tire pressure (since the sidewalls are now weak), sun and heat also add to this deterioration. Hard surface riding (concrete, etc.) has no give and only exacerbates this issue.
The solution: check your tires often for the right air pressure.

Unofficially, I have cracks in the sidewalls of one of mine and I think they are just due to the rubber being too hard. After a while it just gives way. It has been pressurized at about 50-60 psi for a couple of years though, and 99% in the shade. In no way would Coker Tire be responsible, though, because of the over-pressure.

At the bike shop I worked at, the word was that there is no good treatment for tires. I don’t know that by experience, though.

"Unofficially, I have cracks in the sidewalls of one of mine and I think they are just due to the rubber being too hard. After a while it just gives way "

You may be right about the hard rubber. Tom Miller (the unicycle facory) told me today that tire hardness is due to the amount of carbon the manufacturer puts into it.

It’s a coker tire thing and I believe it has to do with the rubber compound they use, Coker Tire’s main buisnes is making tires for vintage cars and trucks and I guess they use an old type of rubber. I allways store my coker out of the sun and keep the presure up, I believe low pressure is worse than high pressure because when the tire is low the sidewalls flex more. I guess I will give something a try but I think it probably won’t help but I will see. I have never had a tire fail because of the cracks so I guess it’s no big deal. I wonder what the tire is like that comes on the new qu-ax 36er is like and if it will be available sometime in the near future. It would be nice if it’s lighter.

this thread carries some discussion about the two tyres

Cracking Cokers and Tubeless

Low pressure may well speed sidewall cracking.

Makes me wonder about TUBELESS COKERS & SIDEWALLS. I’d be very interested to read about tubeless effects on sidewall cracking and air retention, etc.

How are you tubeless converts doing? Anyone know?

I think high pressure does the sidewall thing more.

At least that’s my experience.

I ride with 50-60psi in my coker nowadays. It definately does the sidewall thing more than before I got a track pump. It may be because extra pressure makes the tyre go into a slightly different shape from the one it’s meant to be in. It definately changes the wear on the tread of the tyre to be a bit more along the centre line.

The sidewall thing doesn’t seem to do anything, I’ve not had any sidewall problems yet.

qu-ax tyre is heavier by the way.



What does “the sidewall thing” mean? Is it cracks in the sidewall?


I would agree that riding with LOW pressure would flex the sidewall more and make it more likely to crack. I haven’t done that experiment with a Coker tire. I always have it well over the 32 psig MAX rating. I have seen no sidewall problems and I’ve worn the tread off of two tires, nicely down the center as Joe said.


How many tires have you gone through? Are you talking about tires you ship out? I would doubt that because they’re new when you ship them.

Yes these are sidewall cracks that appear after the tires have been mounted for a while, not new ones. I have put a bunch of tires on wheels that I have shipped out, but personally I have put more wear on freestyle and 29er tires. That should change this summer, but who knows. My body seems to like the 29er (Big Apple is actually a 30"). So I haven’t replaced a personal Coker tire yet due to wear. I have replaced several freestyle.

I’m not sure that the cracks are due to flex as much as stretch. However, perhaps only a tire engineer would be able to tell for sure. Both of the tires I have had here for a long time (i.e., for over two years) have been about the same pressure (say, 50 psi or so) so I can’t contrast them.