Is a Cracked Windshield a DOT Violation? Truck Windshield Rules, Explained

Quick answer: sometimes. A small chip off to the side might be perfectly legal. A crack in front of the driver can put your truck out of service on the spot. The difference comes down to where the damage is and how big it is. Here’s exactly what the federal rule (FMCSA 393.60) says, in plain English.

What the rule actually allows

The regulation covers the glass from the top of your steering wheel upward (it ignores a 2-inch strip along the very top). In that area, but outside the driver’s wiper sweep, you’re allowed:

• A crack up to ¼ inch wide — as long as no other crack intersects it.
• A chip or damaged spot up to ¾ inch across — as long as it isn’t within 3 inches of another damaged spot.

So one small star-chip near the passenger corner? Probably fine. That’s the good news.

What puts your truck out of service

The danger zone is the sweep of the driver’s-side wiper — the arc the blade cleans right in front of you. A crack or discoloration in that area is an out-of-service item under the inspection criteria. An inspector can park the truck right there until it’s fixed. Same goes for cracks that intersect each other, clusters of chips close together, or anything blocking the driver’s view.

Why a “legal” crack won’t stay legal

Here’s the trap: a ¼-inch crack that passes today doesn’t stay ¼ inch. Road vibration, a pothole, a cold morning after a hot day — glass flexes, and a compliant crack becomes a foot-long violation overnight. Truckers running long interstate miles see this constantly. The crack that was fine at the terminal fails at the scale.

The real cost of “I’ll deal with it later”

An out-of-service windshield doesn’t just mean a fix — it means a missed load, a hit to your CSA inspection record, and downtime at the worst possible time (roadside, off-route, on the clock). Replacing it on your schedule is always cheaper than replacing it on the inspector’s.

Get it handled before it’s a violation

We replace commercial truck windshields starting at $120, with OEM-quality DOT-compliant glass for Freightliner, Peterbilt, Kenworth, Volvo and more. Mobile service — we come to your yard, truck stop, or roadside, same-day, so you’re not driving on a violation or losing a day off dispatch. English and Español.

A note: the officer in front of you interprets the rule, and out-of-service calls can be stricter than the letter of it. When a crack is anywhere near the driver’s side, the safe move is to replace it.