There is one more mechanism there - when the front tire rides over a nail it can can &quot;make it stand&quot; setting it in a position dangerous for a rear tire. That is a known issue and was brought to me by my father that was doing some work at nails factory. Their solution was to limit the maximum car speed to at most 20 km&#x2F;h to give nails time to &quot;lie down&quot; before meeting the rear tire.<p>To make it more than anecdotal evidence one could try to reach statistics about nail punctured tires - if there will be much more rear punctured tires than the front ones, that would support the hypothesis.<p>Of course my father didn&#x27;t listen and punctured his tire. The rear one.

I have experienced a roofing nail puncture as a cyclist. In Australia roofing nails usually are galvanised with a washer to spread the load held by the head across a corrugated sheet of steel or plastic.<p>I was riding at around 35 km&#x2F;hr and believe my rear tyre rolled along the nail from point to head until the tyre hit the washer. The washer then then forced the point of the nail upwards into my tyre, tube and then right through my aluminium rim. There was a very load bang and an near instantaneous loss of tyre pressure. I was lucky it was the rear wheel and not the front so I could keep the bike straight and slow down safely. The wheel wasn&#x27;t ride-able after that.<p>In my car the two times I&#x27;ve had puncture were due to roofing screws which also have a built in washer type flange. Again I think the washer&#x2F;flange acts as a lever helping to flip the point upwards into the tyre. In both cases the car tyre didn&#x27;t deflate but we could hear the screw hitting the road on every tyre revolution so drove straight to the nearest tyre repair shop to get it fixed.

This is a surprisingly long conjecture about how tires are punctured by nails and yet it contains very little accurate information about tires and their construction (such as being lined with steel cables).

I find it amazing when you look at a well-used bike tyre, how much glass and bits of metal shrapnel are embedded in the rubber. When the tyre is new, the rubber is thick enough that small sharp things don&#x27;t make it through to the tube, but they stay in the rubber, and as it wears down those same bits of shrapnel start to become a problem. Usually with an older tyre, once you get one puncture, there are many more on the way, so it&#x27;s time to replace the tyre.

The hypothesis that the nail either punctures on the first rotation, or not at all, misses that something <i>is</i> different on subsequent rotations, namely that the nail experiences centripetal acceleration once it is embedded in the tyre. You could imagine that on first contact, only the tip of the nail sticks into a tread block. Then as the wheel rotates, centripetal acceleration causes the nail to be pulled more perpendicular, and on the second rotation it punctures the tyre when it hits the ground. No idea if this is actually a common failure mode, but it seems plausible at least.

All my road bicycle punctures (few per year) are from tube getting pinched against the rim of the wheel. Usually after hitting the pot hole or curb.

Interesting older blog site - was this once a popular forum these types of questions? Feels like an old school Reddit

I ran over a nail on my bike last week and got an instant flat. The nail was about 3cm long and bent at a right angle in the middle. I had just replaced the tire and tube earlier that day.

Solution: put a large magnet in front of your vehicle.

Related topic - always pay the extra 10% for the tire insurance at Discount Tire; I can&#x27;t believe they aren&#x27;t losing money on this.