More than a quarter (28%) of 2017 model year vehicles do not come with a spare tire as standard, according to research by the American Automobile Association (AAA).

Automakers are eliminating spare tires from new vehicles in an effort to reduce weight and improve fuel economy, says the AAA. But, drivers are being caught out. Last year alone, the AAA rescued more than 450,000 members who were faced with a flat tire and had no spare.

“Having a flat tire can be a nuisance for drivers, but not having a spare could put them in an even more aggravating situation,” said John Nielsen, AAA’s managing director of Automotive Engineering and Repair. “This can turn the relatively routine process of changing a tire at the roadside into an inconvenient and costly situation that requires a tow to a repair facility.”

While new vehicles are equipped with tire pressure monitoring systems that alert drivers to low tire pressure, AAA’s roadside assistance data shows that tire-related problems continue to be one of the top reasons why members call for assistance. Even if drivers do have a spare tire, they often call for roadside assistance rather than attempt to change the tire themselves.

As a replacement for a spare tire, some automakers are including tire-inflator kits that can temporarily repair small punctures in flat tires. However, a 2015 AAA study found that tire-inflator kits have limited functionality and cannot provide even a temporary fix for many tire-related problems, including sidewall damage or blowouts.

“With low-profile tires and the elimination of a spare tire, many newer vehicles are especially vulnerable to roadside tire trouble,” Nielsen said. “AAA urges drivers to make it a priority to check their vehicle’s equipment and know what to do if faced with a flat tire.”