Nearly one-third of 2017 model year vehicles do not have a spare tire as standard equipment, according to the American Automobile Association.

"It was kind of shocking to all of us,” said Jim Sterk, general manager of Lithia Ford in Boise. “Even here at the dealership we were like 'Oh where's the spare?'”

No spare tire is a new trend in cars. It’s an effort to reduce weight, which improves fuel economy, and provides more space.

"It's just one of those things that changes with time and that people are used to,” Sterk said.

But that is leaving some concerned.

“What we typically see as a very basic safety problem fixing a flat tire becomes something much more complicated when there's nothing to change it to," said Matthew Conde, public affairs director for AAA Idaho.

AAA responds to more than 5 million calls for flat tire service every year nationwide. In 2016, 450,000 of those calls were due to missing a spare tire. That typically leads to a vehicle being towed.

"If we don't have that spare tire it's a lot more time and expense for that person," Conde said.

But you’re not automatically out of luck. The spare tire in these new cars has been replaced with an inflator kit.

"It's kind of just like your old bike tube,” Sterk said. “It has the goo that you shoot inside there once you get a flat and then inflate."

That goo or substance fills the hole and then you can inflate the tire with the push of a button.

"The ease of what the inflator kit allows compared to jacking a car in the air, getting the lug bolts off, which can be very tough for some folks, very difficult," Sterk said.

However, it doesn’t work in every situation.

"Those inflator kits are only designed for small punctures or situations that are relatively minor,” Conde said. “If it's something large or a side wall blow out or major damage type of situation the inflator kit really won't work for that."

“That would be a situation where you call roadside assistance,” Sterk said. “They come and get you and bring you to the nearest dealership and get you fixed up."

If that makes you uncomfortable, AAA recommends having a fifth option tire.

"There's not probably going to be space for one, but we're looking at if you're on a long road trip and you're in a situation where you're in a remote area you want to make sure you add the fifth tire as essential equipment for your safety,” Conde said.

The inflator kit is only a temporary fix. It’s meant to get you going so you can take your car to be repaired.