Tire Blowout or Flat Tire on a Semi: Stopping Safely and What to Check

The direct answer: get the truck stopped safely and do not continue on a flat. Federal rules say no motor vehicle shall be operated on a tire that is flat or has an audible leak, has tread or sidewall separation, or has ply or belt material exposed (49 CFR 393.75(a)). On a dual, the tire next to a flat is carrying the load of two, heating up, and often fails within a few miles.

First: can you keep driving?

No, apart from moving to the nearest safe place to stop. That applies to a flat inside dual as much as to a steer tire. (916) 571-8888.

If a tire lets go while you are moving

1. Hold the wheel firmly and keep the truck straight. A steer-tire failure pulls hard toward the failed side.
2. Do not brake hard. Stay off the brake until the truck is under control, then slow gradually.
3. Ease off the throttle and let the speed come down.
4. Signal and move to a safe stopping place, as far from traffic as you can get.
5. Hazards on and warning devices out. Placement distances are in our warning triangles guide.

Why limping on a flat dual costs more

• The remaining tire is overloaded, flexes far more than it was built to, and overheats.
• The flat tire is dragged and shredded; the casing is no longer repairable or retreadable.
• Flailing tread takes out mud flaps, lights, air lines, wiring and fenders.
• Heat from a tire run flat can start a fire at the wheel end.
• A wheel run on a flat can be damaged at the bead seat and flange.

An inside dual can be flat without looking it. A tire gauge on every tire at the pre-trip finds it; a glance does not.

What to inspect after a blowout

• The mate tire on a dual. If it ran any distance beside a flat, have a tire professional inspect it before trusting it.
• The wheel — cracks, a bent flange, damaged stud holes.
• Brake chamber, hoses and ABS wiring at that wheel end.
• Lights, mud flap, fender and anything the tread reached.
• The hub — heat, a leaking seal, play. A dragging brake or a failing bearing may be why the tire overheated in the first place.

Why tires fail

• Underinflation, the most common. A tire low on air flexes, heats and comes apart from inside. Slow leaks from a nail, a valve stem or a bead do the same over days.
• Road hazards and impact breaks from potholes and curbs.
• Overloading or a load shifted onto one side.
• Mismatched duals. Different diameters or pressures put the load on one tire.
• Heat from the wheel end — a dragging brake or a bearing (trailer brakes dragging, wheel seal leaks).
• Worn or damaged casings — tread below the legal minimum, cuts to the cords, old repairs. Minimums and wear patterns are in our tire wear guide.
• Alignment and suspension faults that wore one edge thin (alignment signs).

When you call

Tell us where you are and which way you are headed, the tire position (steer, drive or trailer; left or right; inside or outside), the tire size from the sidewall, whether the wheel looks damaged, and what else the tread hit. With that we can tell you whether it is something we can handle where the truck sits or at the shop, or whether a tire service truck is the right call. See tire repair and replacement and emergency roadside assistance.

Common questions

Can I drive on one tire of a dual to get to a shop?

The rule prohibits operating on a flat tire, and the practical reason is the mate: it is overloaded and overheating. Stop somewhere safe and have it changed there.

Does the other dual need replacing after a blowout?

Not always, but it needs a proper inspection. A tire that carried a double load for miles may have internal damage that does not show on the outside.

Why do I keep losing trailer tires on the same axle?

Look past the tires: a brake dragging at that wheel end, a bearing running hot, an alignment fault, or a slow leak nobody is gauging.

How much tread is legally required?

At least 4/32 inch on the front tires of a truck or truck tractor and 2/32 inch on the others, measured in a major tread groove (49 CFR 393.75).