How E-Bike Tires Get Punctures

A tire goes flat because air escapes, and the way it escapes leaves clues. A slow hiss points one way. A bang points another. Sorting the clues takes a minute and tells you what to look for before you touch the tube.

First, where the hole is

Sheldon Brown's flat tire article puts it plainly: a tire goes flat because there's a hole in the inner tube. There may or may not be anything wrong with the tire itself, unless it's tubeless.¹

That's why it helps to know the five common kinds. Four apply to all tires, and one applies only to tubeless ones.¹

The kinds of flat

Slow leak. The tire loses air over a long time. It's normal for a tube to lose some air over a period of weeks, so a gradual drop isn't always a hole.¹

Puncture. Punctures are caused by running over sharp things that poke a hole through the tire and into the tube. Glass slivers, thorns, nails and bits of wire are the usual list.¹ The same article reminds you not to forget to remove the pointy thing from the tire before the tube goes back in.¹

Pinch flat. Also called a pinch cut or a snake bite. It comes from hitting stones, curbs or sharp edges of holes in the road surface.¹ The tire compresses and bottoms out, and the tube gets pinched between the rock and the rim.¹ The telltale sign is usually two small holes in the tube, which is why it's called a snake bite: the two holes look like the wound made by the fangs of a snake.¹

Blowout. A sudden loss of air, usually with a loud bang.¹

Burp (tubeless only). The tire loses its seal to the rim. The same article says it happens due to hard landings or cornering and is more likely with low air pressure.¹

Sidewall cuts

A cut in the side of the tire can be a flat's cause too. Sheldon Brown says a quick look before you remove the tire can help. There may be a nail sticking out, or a hole in the sidewall, or some other obvious problem.¹

What makes flats more likely

Pressure plays a part, and it works both ways. An underinflated tire will be prone to pinch flats. An overinflated tire is more prone to damage from sharp rocks and similar road hazards.²

Where to find the limit on your own tire is covered in the pressure marking notes.

Tire construction matters too. Wikipedia notes that some tires include an extra layer between the tread and the casing to help prevent punctures, either by being tough or simply by being thick.³ Look at your tire maker's page to see what yours has.

After you've found the cause

What to do next, whether patching or swapping the tube, is covered on a later page of this site. Follow the instructions in your bike's manual and from your tire and tube makers. If you aren't sure the tire itself is safe, have a bike shop look at it.