Get somewhere safe first
A flat is an inconvenience on a level shoulder and a genuine danger on a blind curve. Keep rolling slowly, hazards on, until you reach a straight, flat, firm stretch well off the road, even if it costs you the tire. Rubber is cheap. Set the parking brake, put the car in park or in gear, and wedge something solid behind a wheel on the opposite end of the car. If you are on a highway with traffic passing at speed a few feet away, stay belted in and call for roadside help instead.
What you need
The spare, the jack and the lug wrench usually live under the trunk floor. The owner's manual shows where they are and, more importantly, where the jack is allowed to touch the car. Many newer cars carry no spare at all, only a can of sealant and a small compressor, which is worth knowing before tonight.
The sequence
- Pry off the hubcap if there is one, then break each lug nut loose a half turn while the tire is still on the ground. Use your body weight on the wrench, and turn counterclockwise.
- Place the jack under the marked jacking point nearest the flat and raise the car until the tire clears the ground by an inch or two. Never put any part of yourself under the car.
- Remove the nuts, keep them together in the hubcap, and pull the wheel straight toward you.
- Seat the spare on the studs and thread every nut by hand until it is snug.
- Lower the car until the tire carries weight, then tighten the nuts in a star pattern, crossing the wheel each time, as tight as you can make them.
After you are rolling
A compact spare is a temporary part. Most are rated for about fifty miles at no more than fifty miles an hour, and the limit is printed on the sidewall. Check its pressure at the first gas station, because spares sit unused for years and go soft. Stop after a few miles to tighten the nuts once more. Then take the damaged tire to a shop: a puncture in the tread can often be patched for very little, while damage to the sidewall means a new tire.
Tip Practice once in your driveway on a dry afternoon. The first time you loosen a lug nut should not be at night, in the rain, on a shoulder.
