How to Prevent a Flat Bike Tire

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Nothing is 100% effective in preventing you from getting a flat tire on your bike. You do, however, you have a number of options that can greatly reduce your likelihood of getting a flat. With this advice and/or products, you may never need to fuss with tube punctures or patch kits again.


Tire Pressure

Your first strategy should always be to make sure you are riding with the proper tire pressure.

Each tire has a preferred air-pressure range, which is measured in psi (pounds per square inch). Look on the tire sidewall for the recommended pressure. As a general rule:

  • Road tires should run between 100 to 140 psi.
  • Mountain bike tires should run between 30 to 50 psi.
  • Urban and casual bike tire should run between 60 and 80 psi.

Under-inflation can lead to problems with "pinch flats." This can occur when you hit a bump and your under-inflated tire compresses all the way to the rim, causing 2 small holes that resemble a snake bite. Over-inflation, on the other hand, doesn't cause flats although it's possible to blow out the tube in extreme cases.

Use a tire pump or gauge to check your pressure. Higher-end tire pumps will include a psi gauge, but if you have a lower-end pump, you'll need to carry your own tire pressure gauge. Be sure to know whether you have a Presta or Schrader valve stem (the slimmer Presta valve needs to have the top nut unscrewed before checking pressure).


Basic Tire Care

It's a good idea to periodically inspect your bike tires for embedded glass, rock shards or other sharp objects, especially after riding a route that has substantial debris. These small embedded items may not cause an immediate flat but can slowly work their way through a tire to eventually cause a puncture. Use your fingernail or a small tool to remove this debris before it causes a problem.

Periodically check your tire sidewalls and tread for excessive wear, damage, dryness or cracking. Tires with any of these symptoms increase your risk for a flat tire. If unsure about their condition, ask a bike pro at your local REI or other reputable bike shop to evaluate your tires.


Tube Sealants

This option is handy because you can repair an existing flat tire with it or use it as a preventive measure to avoid future flats. The concept is simple: Squeeze in a bit of sealant through the valve stem to coat the inside of the tube. In the case of a small puncture or cut, the sealant quickly fills the leak and creates a plug that often outlasts the tube or the tire around it.

REI carries 2 types of sealant. The Slime brand is designed to be injected directly into Schrader-type tubes only; the Café Latex brand is designed to be injected into Presta-type tubes or tubeless tires. Café Latex requires use of a no-mess injector which is sold separately.

Some tubes (with both Schrader and Presta valves) come "pre-Slimed" to offer a preventive approach to flat tires. These tubes are typically a thicker thorn-resistant variety, that when pre-injected with Slime, offer an excellent flat-avoidance strategy.

The downsides to sealants? Some can be a little messy to install, and sealants alone do not protect against large gashes or cuts.



Tire Liners

A tire liner is a thin strip of extruded-plastic that fits between the tire and the tube. This extra layer greatly reduces the chance of puncture flats from thorns, glass or other sharp objects. Liners are popular and work well, but they do add 6 oz. or more to the weight of your tires which adds noticeably to your rolling resistance in higher performance tires. However, if you live in an area with lots of thorns or road debris, liners could be well worth the weight.

A reviewer nicknamed iGottabike offers the following nifty installation tip on

When installing liners, place your tire on the rim as you usually do to fit the inner tube within the tire (one bead on rim/one off). Fit the tube into the tire. Pump a little air into the inner tube to expand it just until the tube begins touching the inside of the tire (it won't require much!). THEN, slide the liner between the tube (lightly inflated) and the tire. The pressure of the inflated tube will keep the liner held in place against the inside of the tire preventing liner from shifting resulting in tube chaffing or cutting (I have never had the liner shift or chaff when installing this way). Once the liner is in place, if you can't get the tire back on the rim you probably have a tad too much air in the tube - let a little out, pop the tire over the rim and fill to recommended/desired pressure. Happy (bike) trails!


Puncture-resistant Tires and Tubes

Another option is to change out your tires to ones specifically designed to resist flats. These tires won't feel as speedy as standard bike tires, but bike-commuting customers have told us that they experience flats much less frequently when using them.

How do they work? Many tires makers employ a durable belt of aramid fibers (such as the well-known Kevlar® brand) to resist punctures; others simply increase the tread thickness. These tires are marketed by a variety of proprietary names: the Serfas Flat Protection System, the Continental Safety System, the Michelin ProTek reinforcement system and so on. The downside of these tires is that they are relatively heavy which reduces your pedaling efficiency.

Finally, consider using thorn-resistant tubes. They are simply thicker (and heavier) versions of conventional tubes.


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