Jim’s Tech Talk: Is that Tire Dead Yet?

Avoid Early Re-tire-ment

Sooner or later it happens to most roadies. You drop a cool $130 on a sweet new pair of clincher tires and then immediately ride over something that slices the tread. Is that pricey new rubber ruined? Does the gash make it unsafe?

Great questions. The good news is that in most cases, a tread slice isn’t a tire trasher. Let’s see how to evaluate it and repair it (if necessary) and how to reduce the chance of getting cuts.

Assess the Damage

During a ride, the key is whether the tread-slicing object also penetrated the tire’s casing. If it went through, you probably flatted. If not, look closely inside the slice to gauge any casing damage. Make sure the tube isn’t bulging and will soon blow out.

The casing is usually tan and looks like woven material. If it’s been sliced but it’s clear that the tube isn’t trying to protrude, you can keep riding.

But if the tube is even slightly bulging, remove the tire and cover the casing slice from the inside. If you don’t, you’ll likely get to experience a sonic boom down the road when the tube finally pushes through.

If the tread slice is longer than 1/2 inch (1.25 cm) and the casing was also cut, or if what you hit damaged the tire sidewall, spin the wheel to check for deformation. It usually looks like an S wiggle in the tread and it will make an annoying bump with each revolution while you’re riding. In this case, the tire is kaput as soon as you (gingerly) get home.

Repair Techniques

You can ignore a small tread cut that hasn’t penetrated the casing.  (continued)
It’s unlikely you’ll ride over something else that finds the same defect. But if it bothers you, close a small slice with super glue or fill it with silicone sealer or Shoe Goo.

If the casing has also been cut, patch it from the inside (also called “booting”). Simply remove the tire and cover the damaged casing. In a pinch during a ride almost anything will work — a dollar bill, wrapper from an energy bar or gel, roadside trash. I carry Park Tool’s tough, peel-and-stick Emergency Tire Boots (3 for $5) in my seat bag.

If you’re using a non-adhesive patch, you need to carefully hold it in place as you install the tire. In your home shop, put regular household rubber cement on the patch and inside the tire, let the glue dry and then apply the patch. Dust it with talcum powder so the tube doesn’t stick.

If it’s all you have on a ride, use a patch from your tube repair kit. These patches aren’t made for booting, don’t stick well to casings and may not stop a tube from bulging through a significant slice, so don’t overinflate.

Tip: Make casing patches by cutting 1×2-inch (2.5×5-cm) pieces from old jeans or canvas. Saturate them with rubber cement, let them dry, put them in a baggie and keep them in your seat bag. They’ll stick to the casing without any additional glue. Duct tape works too. Wrap some around a tire lever.

For serious cuts and casing damage you need serious reinforcement. The best way is to use an old tire of the same make and size you’re fixing. Cut a piece that overlaps the damaged section by an inch on each end, then cut off the beads so they can’t interfere during installation. This boot should now fit neatly inside the sliced tire, letting you ride it for many more miles. It may not roll perfectly, but it should be safe.

Avoid Tire Cuts

The best defense against tire cuts is also the easiest: Watch where you’re going and steer clear of all the debris you can. If you ride with friends, help each other by pointing and calling out glass, gravel, potholes and other dangers.

Also important is reasonable inflation pressure. Hard tires cut easier. For most roadies on 700×23 clinchers, pressures in the range of 95 to 105 psi provide good performance, protect against pinch flats and have the resiliency necessary to absorb sharp things with less tread damage.

Although tires often are labeled with maximum pressures of 120-140 psi, if you inflate them that hard you’re going to need this column’s advice a lot more often.

Republished from Jim’s Tech Talk in Road Bike Rider with their permission.

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