Your front or rear tire blew out while you were riding your bike. Instead of getting from A to B by bicycle, you had to walk… with the bicycle by your side.
Or maybe your tires have high mileage, are having a hard time holding air, and are showing alarming signs of wear and tear. So you’re wondering if it’s time to fit your bike with new tires before one (or both) of them explode on you when you need it the most.
Different things can lead you here, but the question is almost always the same: Can bicycle tires explode?
Bicycle tires can blow out for many reasons. Usually, it happens either because the tire is overinflated (and can’t handle the pressure) or because it’s underinflated (and the tube gets pinched between the tire and the rim). It can also happen because the tire is too old or worn out.
What’s interesting is that a tire can blow out at any time, whether you’re putting air in it, riding your bike, or after you’ve parked it.
When it happens, it happens with a bang; it’s loud and dramatic. The hole caused by the blowout is so big that the tire goes flat momentarily. In many cases, it’s also irreparable and requires replacement of the inner tube.
Why Do Bike Tires Blow Out?
Overinflation
I have one word for you: pressure.
A bike tire—and its inner tube—is basically a container for air, made of fabric, rubber, and about 300 additives that give it strength and durability.
Rubber consists of long chains of molecules called “polymers.” These chains are so long that they get tangled up in themselves, giving the rubber elasticity and allowing it to strech.
As elastic as rubber is, it cannot stretch indefinitely. The butyl rubber from which inner tubes are made (and which lines the inside of tubeless tires) is no exception. Just like air escapes through your lips when you puff up your cheeks to much, air will find a way to escape through the tire if you overfill the tire with it.
Tip: Before every ride, whip up your tire pressure gauge or bike pump and check the tire pressure. If you’re at school or work and you don’t have one handy, you can do this by feel.
Underinflation
Many are surprised by the fact that too low air pressure can cause the tire to burst, but there is a simple and logical reason for this.
If one of the tires on your bike is soft and you nevertheless go on a ride, the inner tube will deform under the combined weight of yourself and the bike. As a result, it can get pinched between the beads of the tire and the edges of the rim (and this happens a lot).
While riding, this can cause snakebite punctures—two symmetrical punctures on both sides of the tube where the tire meets the rim that, once you’ve removed the tire and taken out the inner tube, look very much like a snake bit into the rubber.
But a pinched tire can blow out long after you’ve parked your bike, especially if you’ve parked it outside in the sun on a sweltering summer day. It does so because the pinch thinned out the rubber and damaged the polymers in it.
When you ride a bicycle, the tires roll on the road… with a certain amount of friction. This friction generates heat, and the heat causes the air inside the tube to expand. This increases the tire pressure, which in turn exasperates the weakness in the rubber. Bam!
Tip: Once again, make it a habit to check your tire pressure before every ride. You don’t have to do this fanatically; a check with the tire pressure gage at home and a quick squeeze at college or work will do.
Old And/Or Worn Out Tire
Rubber isn’t meant to last forever. As a general rule of thumb, bicycle tires have a lifespan of 4 to 6 years from the date of manufacture. After this time, they begin to dry rot and their lose their elasticity.
Simply put, a tire that’s too old is a tire that gives way under pressure. (And no matter how much you know about tires, you know for sure that this is the last thing you want from them before, during, or after a ride!)
Another culprit is wear and tear. After a couple of thousand miles, most tires wear out. The treads thin down. The beads weaken. Cracks form on the sidewalls, showing cord and causing deformities.
All of this means that an old and worn out tire doesn’t roll as smoothly as it should. On clincher and tubular tires, this can cause blow outs in the inner tube. Tubeless tires, contrary to what some people think, can also burst.
Tip: Replace your tires and tubes preventively every few years and/or every few thousand miles. It is better to do this on your schedule than to have to adjust your schedule when you’re forced to it anyway.
Hot Weather
You thought you only had to read the weather report to know when to take your raincoat on a cloudy day, didn’t you?
As it turns out, a heat wave can do more damage to your bike’s tires than you probably think. Especially if it’s midday and you’ve parked your bike on a stand in the sun.
In high-school physics class, they taught us that air expands when it’s hot and contracts when it’s cold. Since tires are rubber containers for air, this means that the pressure in them will increase on a hot day and decrease on a cold day.
It’s even worse if you leave your bike in the sun. The tires can get so hot that you can fry eggs on them. And if they’re already overinflated or pinched, it’s not hard to see why one of them might pop like a balloon, even long after you’ve parked the bike.
Tip: Keep your tires at 10-20% under the maximum recommended pressure in the summer.
The Bottom Line
Your bike’s tire can blow out for many different reasons. When it happens—or you suspect it might happen—it’s important to make a note of these and rule each one out until you get to the bottom of it.
