How to fix a flat tire


Flat tires happen to everyone, usually at the most inopportune times. But you don’t need to fret, since it’s much easier than you might think to fix it yourself. We’ve put together this simple guide to fixing your own flat tire, specifically by patching a tube.

Vulcanization, a process developed by Charles Goodyear, changes the properties of rubber via chemical reactions. These reactions are what makes rubber work as a tire material. It is also the reason a properly patched inner tube is actually stronger than an unpatched tube.

When done properly, inner tube and patch are bonded at a molecular level, not just adhered together. This means the patch will stretch with the tube as it is inflated, and will last the life of the tube. The vulcanization process is also the reason many attempted tube repairs end in frustration. The self-vulcanizing fluid (rubber cement) needs time to set up before the patch is applied, so pay heed to step 5 below.



Remove the tube. (While it is technically possible to repair a tube without removing the wheel, it is much easier to work with the wheel off the bike.)


Locate puncture. Grab your pump and start reinflating the tube—big holes will be obvious. If the hole proves elusive, hold the tube up near your cheek and ear. You should be able to feel and/or hear most small leaks. For really hard-to-locate holes, immerse the tube in water a section at a time and look for a tiny stream of bubbles. Some flats are caused by pinching the tube against the rim. This usually creates a pair of punctures, or a “snakebite”—make sure you find and patch both.


Prep the surface. Most patch kits come with sandpaper, use this to rough up an area around the hole a few millimeters larger than the patch you are using. If you have a choice, select the smallest patch that covers the hole. If sandpaper isn’t available, a rock or any other rough surface can be used, just make sure there isn’t any debris left on the tube.


Apply the glue. Apply a thin layer of vulcanizing fluid to the tube, enough to cover a spot a few millimeters larger than the patch.


Wait five minutes. Find something to do. Get out your smart phone, roll a cigarette, take a quick nap, but DO NOT skip this step. Getting that molecular-level bond depends on giving the glue enough time to set up.


Apply patch. Peel off the foil, center the patch, and press down firmly. Leaving the clear plastic on the non-business side of the patch keeps it from sticking to the inside of the tire, and keeps the glue off your fingers. With the tube on a flat surface, use something not-sharp (tire lever, screwdriver handle, rock) to press the edges of the patch into the tube.


Install and inflate tube. This is a permanent fix, and assuming you followed all the steps properly, there is no need to replace the repaired tube with a new one.


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