A spare tire in a car.

Q. I was stunned to discover that my new car doesn’t have a spare tire. Was I ripped off?

A. Not really. About a third of new cars today do not come with a spare tire, though they may be equipped with a compressor and sealant kit to temporarily fix a flat tire. Some cars without spares come with “run-flat” tires, which are designed to operate for a limited distance after losing air from a typical puncture.

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Carmakers are skipping the spare because of regulatory pressure to squeeze more miles out of every gallon of fuel: Ditching the 40 or 50 pounds that a tire and jack usually add to a car’s weight helps to increase fuel economy slightly. (It also incidentally increases automakers’ profits because they don’t have to pay for those parts.)

The problem is that a sealant kit won’t help drivers if a tire’s sidewall gets sliced or if the flat is caused by more extensive damage than a tread puncture. If you want to be prepared for any type of flat tire, some retailers and car dealers offer spare-tire kits, including a tire, jack, and lug wrench, starting at about $150.

“Know how your car is equipped before you take delivery,” says Gene Petersen, CR’s tire expert. “Don’t assume the car you’re about to buy has a spare tire. The best time to find out is in the showroom—so you can also use it as a negotiating point—not on the side of the road after you’ve had a flat.”

Editor’s Note: This article also appeared in the September 2018 issue of Consumer Reports magazine.