One night Sarah Hong, then a tow truck dispatcher, got a call from a woman whose two-seater sports car had a flat tire. “No worries, right, since her husband knows how to change a tire,” says Hong. “Then they opened the trunk and discovered for the first time that their lovely new car didn't come with any spare tire at all.”

Spare tires are disappearing from auto dealer showrooms. To improve fuel economy by reducing weight, manufacturers sold 36 percent of their 2015 model-year vehicles without one, according to AAA.

This is a “growing concern” for AAA, says Greg Brannon, the organization's director of automotive engineering and industry relations. “Being stranded on the side of the highway can be dangerous and scary for any driver, and not being able to remedy a flat tire quickly worsens the situation.”

Here’s how to avoid that exact predicament.

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Know what's in your trunk. When you buy a new vehicle, ask if it comes with a spare tire. Otherwise they might not volunteer that it doesn't.

If there's no spare, “ask the dealer about adding a spare tire as an option,” says Brannon. “Although this is an up-front cost, it’s a good safety precaution.” Make sure the option also includes a jack and tire iron.

If you do have a spare, periodically check its air pressure and re-inflate as needed. Also, spare tires can age while sitting in the trunk. Consult your owner's manual to find out when to replace it, even if it has never been used, according to the National Highway Traffic Safety Administration. You don't want to be sitting on the shoulder with two flats instead of one.

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Study up on tire inflators. Instead of a spare, some new vehicles come with a tire inflator kit. Today's models are more high-tech than the old-fashioned aerosol canisters that folks used to keep in the trunk. Like a small pump, it temporarily re-inflates the tire in a matter of minutes with pressurized gas. At the same time, it coats the interior with an air-resistant sealant.

Inflators work well only under limited circumstances, such as when a nail punctures the tire and remains embedded in it, according to tests conducted by AAA. “In situations where there’s a blow-out, side wall damage occurs or a tire is damaged by a curb strike, an inflator kit cannot provide even a temporary fix,” says Brannon.

If you buy one separately, prices vary widely, with many models running under $100. Brannon advises kit owners to familiarize themselves with the user's manual before hitting the road.

After you use an inflator, take the tire to a garage for repairs. Be aware they may charge you extra to clean out the sealant. If the sealant makes the tire unserviceable, you might lose your tire manufacturer's limited warranty, according to Consumer Reports.

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Know the limitations of run-flats. About 12 percent of new vehicles come with run-flat tires, according to Edmunds.com. These are designed to temporarily resist going flat after a puncture. You can still drive on them for around 100 miles at 50 mph. (If you drive too fast or too long after a puncture, the tire can disintegrate.) That should be enough to get you to a service station. But you might have to wait overnight for a replacement tire, unless you can find a dealer that stocks these tires.

Many run-flat tires aren't repairable. If damaged, you have to buy a new one — and they cost more than standard tires. Thirty-one percent of run-flat owners have had to replace at least one tire, compared to 19 percent for standard tires, according to J.D. Power.

Run-flat tires don't always work in the case of sidewall damage. “Even run-flat tires cannot remedy all situations,” says Brannon.

Having a spare tire is more important than the convenience of an empty trunk. Flats happen, so be prepared.

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David Arv Bragi is a freelance journalist and marketing consultant. He has been writing about health and safety issues since the 1990s and currently lives in Portland, Oregon.