Your tire is losing air. You drive to the gas station and learn you’ve "picked up a nail." The guy says he can fix the tire in 10 minutes with a "plug." He doesn’t even have to take the tire off the rim. Ten bucks. Wow. Sounds pretty good. And what’s the worse thing that can happen if it doesn’t work? It’ll leak again, right?

Actually, an improper patch or plug repair can cause the tire tread to peel off the tire. That, in turn, can cause the vehicle to become uncontrollable, leading to the most dangerous type of accident there is — a rollover. And it happens more often than you’d think.

The weak part of the tire is where the steel belts bond with the tire’s shoulder. An improper "on the Repairable Area of Tirewheel" repair can allow moisture to get to the steel belts and weaken the bond. That’s what causes the detread. The three things to remember are:

1. No on-the-rim repairs. The tire must be dismounted so that the tire can be properly inspected and sealed against moisture. If the guy at the garage says he can fix the tire without taking it off the rim, he isn’t doing you a favor. He is putting you and your family at risk.

2. No repairs near the shoulder. The shoulder of the tire is the weakest part.  So only those holes in the middle of the tire can be repaired.  If you pick up a nail near the shoulder, you need a new tire.

3. If you decide to get a new tire, the new tread must go on the rear axle. Installing the new tread on the front axle can lead to a loss of control and rollover for reasons unrelated to tread separation.

Gas station mechanics are supposed to know better. That’s their job. But many don’t.