Can Glass Puncture a Tire?

Here are some tips and tricks if your vehicle drives over broken glass.

Benjamin Hunting | 

Jun 7, 2024 | 3 min read

Shutterstock

Let's face it, roads aren't always free of debris. Road hazards can cause drivers to be concerned about the health of their tires and the safety of their vehicles. Broken glass is one of the most common hazards encountered on highways and city streets, but is it something to be worried about behind the wheel?

Here's a look at when and why you should be concerned about a tire puncture after driving over broken glass.

How Strong Are Modern Tires?

First introduced by France's Michelin more than 75 years ago in 1946, radial tires were a vast improvement over the bias-ply tires they replaced. They became standard on many new cars sold in the United States by the 1970s.

Radial tires feature a rigid design that is nevertheless flexible enough to absorb impacts with rough surfaces, with layers of steel belts and nylon helping to dispel some of the energy that would have punctured an older bias-ply tire. The latest radials are getting better at resisting punctures. However, there are still some scenarios where even modern radial tires have weaknesses.

Street tires are designed primarily with tread strength in mind, so their sidewalls are vulnerable to gashes or cuts that can compromise their structure. This is the reason that off-road tires — which are often operated in environments where razor-sharp rocks are likely to be encountered — feature armored sidewalls that include materials such as aramid and Kevlar.

How Glass Compares to Other Road Hazards

It's common to encounter broken glass when out on the road, usually after it has been left behind following a car accident. It's natural to be worried about driving over a pile of glass shards and suffering a blowout, puncture, or other tire damage.

Fortunately, this is rarely a cause for concern. Broken automotive glass is usually found in pieces too small to present a seriously sharp edge and can easily be shrugged off by modern radial tires. If the glass does penetrate the tire tread, it's likely to do only surface damage and not be able to penetrate the steel belts that give the tire its structural integrity.

Screws, nails, bolts, and other pieces of metal you might encounter on the road present a greater danger to tires than glass. Anything long, thin, and sharp is more likely to puncture rubber and steel belts and can embed itself and lead to a leak or a potential blowout. A sharp metal edge, such as from an abandoned car part on the road surface or shoulder, can also slash a sidewall.

When You Should Be Concerned About a Glass Tire Puncture

There are a couple of scenarios where broken glass can lead to a tire puncture.

If your tires are old and worn, there is less rubber in the tread to protect them from being penetrated. Although automotive glass is unlikely to pose a threat, driving over broken bottles is riskier with older tires. Broken bottle glass is also dangerous to brand-new tires. With their curved pieces and long edges, this type of glass can slice a tire's sidewall.

Benjamin Hunting

Benjamin Hunting is a writer and podcast host who contributes to a number of newspapers, automotive magazines, and online publications. More than a decade into his career, he enjoys keeping the shiny side up during track days and always has one too many classic vehicle projects partially disassembled in his garage at any given time. Remember, if it's not leaking, it's probably empty.