What to carry for flat tires

The tire kit we carry on roadside calls: what each piece is for, and where the cheap version is fine.

Flat tires are one of the most common roadside calls. Most of them end one of two ways: the spare goes on, or the tire gets plugged and aired up so the driver can get to a shop. This is the kit that covers both.

First: make the spot safe

Before anything comes out of the bag, get the car as far off the road as you can, hazards on, and put out cones or triangles behind it. Chock the wheel diagonally across from the flat with wheel chocks so the car can't roll off the jack. On a highway shoulder, work from the side away from traffic whenever you can.

Getting the lug nuts off

Loosen the lug nuts while the tire is still on the ground. Factory lug wrenches are short and bend easily; a 24" breaker bar breaks loose nuts that were put on with an impact gun, and a telescoping lug wrench is a good lighter option. If there's a locking lug nut and no key in the car, a wheel lock extractor set (in Sockets and Extractors) gets it off.

Lifting the car

The scissor jack in most trunks works, slowly. A low-profile floor jack is faster and far more stable, and it fits under lowered cars. We recommend the Harbor Freight Pittsburgh 2.5 ton aluminum jack over anything on Amazon, with a replacement pad because the stock rubber falls off. Always lift at the car's jack point, never under body panels, and never put any part of yourself under a car that's only on a jack.

Putting the spare on

Snug the nuts by hand in a star pattern, lower the car, then tighten them in the same star pattern. Most cars call for roughly 80 to 100 ft-lbs; the exact number is in the owner's manual. A click torque wrench gets it right without guessing, and stops you from over-tightening with an impact gun. Tell the driver to have the nuts checked again after 50 miles or so, and that a compact spare is only for short trips at low speed.

Plugging instead of changing

A plug is a fix to get the driver to a shop, not a permanent repair. It's only for a puncture in the tread, like a nail or screw. Never plug the sidewall or the shoulder, or a hole bigger than about a quarter inch; those need a new tire. The BlackJack KT-340 is expensive but the kit pros trust. The 68-piece kit is the budget option and does the job for occasional use.

Air and a quick check

After a plug, or when the spare is low (they often are), air it up with a 12V inflator to the pressure on the sticker in the driver's door jamb, not the number on the tire. Check it with a gauge, and listen for the plug hissing. While you're down there, a tread depth gauge takes two seconds: under 2/32" means the driver needs new tires soon, and it's worth telling them.