Car Tires Run Over Glass
Auto Parts,  Cars

Can Car Tires Run Over Glass?

You recently bought a set of all-purpose tires that are marketed as being able to conquer any terrain and handle the most brutal of winter weather conditions. However, as the flagger turns his sign and directs you to drive slowly through the accident scene, you can’t shake the feeling that the glass scattered all across the intersection is going to shred your new tires.

Car tires can run over the glass because nearly all major tire brands for passenger vehicles have used steel belt technology beneath the rubber tread since the mid-1970s, so it is very unlikely that glass would puncture your tires and cause a major blowout.

However, as with most things in life, you can never say “never.” While there is basically no chance that glass on the highway will do any significant damage to a normal car tire in good condition, it is up to you to know if you may be an exception. If your tires are old, worn, or heavily abused, then the chances increase that running over glass may cause an issue.

Can Windshield Glass Pop a Tire?

windshield glass on the street won't pop tire

No, generally speaking, windshield glass cannot pop a tire.

First and foremost, essentially all modern passenger vehicle tires are equipped with steel belts beneath the rubber tread, negating the damage that sharp objects can do when piercing the rubber of the tire.

In addition, the windshield glass is designed to “conveniently” break. It takes a significant force to break a windshield from a car, but if some major impact causes the glass to shatter, the pieces of the windshield will not be sharp.

This “tempered glass” that is found in the windshield of cars is designed with rapid heating and cooling processes so that in the unlikely event that one of the windshields breaks, it will break into tiny little pieces that mimic pebbles.

Windshields were designed like this to protect passengers. It would be a terrible thing to get into an accident and avoid any bodily injury only to have the windshield fall out and cut the passengers to shreds. With tempered glass technology, if the windshield were to fall out during an accident, the passengers would be met with a lap full of what amount to playground pebbles.

Therefore, when driving through an area in which the highway appears to be covered with windshield glass, do not panic, as this glass will not damage your tires. In fact, when driving through an accident scene, sharp little pieces of plastic from the bumper are more likely to damage your tires than will the windshield glass, although this, too, is unlikely.

What to Do if You Drive over Glass Shards?

run over Shattered glass shard

Steel belt technology in tires has been a major boon for auto owners since its introduction in the mid-1970s. Not only does it make driving safer, as it greatly reduces the chances of sharp objects piercing your tires, but it also extends the life of the tires, saving you money by reducing the frequency with which you need to get your tires changed.

While we have established that broken glass on the highway is extremely unlikely to “pop” your steel-belted tire and cause a blowout, there is a chance that it could do some insidious damage and cause a slow leak. The following are a few ways in which glass may slowly damage your car tires:

  • Old, worn, or abused tires – tires that are nearing the end of their useful life (most likely around 30,000 or 40,000 miles for most brands) or that have seen their tread damaged in off-road activities run a greater risk of having glass puncture them and cause a leak.
  • It is summer warm temperatures cause the rubber in tires to heat up and soften. This makes it easier for glass shards to find their way into the tire rubber and cause a slow leak. Also, consider the friction with the road and the fact that dark objects absorb more heat, making the small likelihood of glass piercing your tire greater in summer.
  • Bottle glass – while we have determined that tempered windshield glass is unlikely to cause your tires harm, other types of glass, such as that used to make beverage bottles, offer no such technology. The sharp, pointed edges of this shattered glass increase the likelihood that your tire could get punctured when driving through a parking lot or alley.

This Video shows what might happen if you run over a glass bottle. 

Even if one or more of the above conditions contribute to glass puncturing your tires, it is not going to make your tire “pop.” Your tire may eventually blow out, but it will occur many miles later due to the following process:

  • Glass cuts the tire – a piece of glass cuts into the rubber of the tire, introducing itself into the steel belt.
  • Foreign particles enter – this wound caused in the steel belt of the car tire allows dirt, air, and other foreign particles to enter the tire, forming a harmful accumulation over time.
  • Corrosion and contamination – the buildup of these foreign particles leads to corrosion and contamination, which will eventually cause the steel belt to separate from the tread. When sufficient separation occurs, you will experience a blowout, which happens about 5,000 to 15,000 miles after the glass initially penetrates your tire.

Therefore, while the postmortem will reveal that a glass puncture was the cause of your tire blowout, it is a little far-fetched to say that running over glass caused your tire to pop.

If you run over the glass and are concerned that the integrity of your tires might be compromised, there are some steps you can take to make sure that you are glass free.

1. Give a Visual Inspection

Tire inspection after run over glass

After driving over a bed of glass, pull your vehicle off the road and into an area where you will have ample space to thoroughly examine all four tires.

Look for any glass that is sticking to the tires. While it is most likely just stuck in the tread, it could be lodged in there due to a hole in the rubber. Carefully clean this glass out with a stick or gloved hand, making a note of how resistant the glass is to dislodging.

In addition, look for any sliced or damaged areas of the sidewall, and keep your ear open for a minor hissing sound that may indicate the release of tire pressure through a small leak.

2. Check Tire Pressure

While it is always a good idea to keep a tire pressure gauge in the glove compartment of your vehicle (they can be bought for as little as a dollar at some auto stores), the reality is that not everyone does.

If you are one of the people who does not have a gauge, then find a gas station that has an air pump and check your tire pressure. Your owner’s manual will tell you where your tire pressure should be sitting, but for most vehicles, it could be around 32 to 36 psi.

When you buy a tire, it might show 34 psi on it, but the best for your car or vehicle may be indicated on the door or frame. You can also look in your owner’s manual. Try not to use anything significantly lower or higher than this range because it could be problematic.

If there is not a gas station with a pressure gauge nearby, keep an eye on your dashboard, as most modern vehicles will have a tire pressure warning light. In fact, some even have the technology to give a tire pressure reading while driving. If a tire pressure issue arises, a small, orange light that looks like an exclamation point will illuminate.

3. Take it to a Tire Center

Tires and Wheels Inspection for glass damage

Most tire shops will run a free diagnosis on leaks. In addition, if the leak is caused by a puncture in the tire tread, most will remove the foreign object and do a complimentary patch. In the unlikely event that a piece of glass punctures your sidewall, you will probably need to get a new tire.