Thirty-six percent of 2015 model-year vehicles were sold without a spare tire, according to a new report from AAA.

Why? Automakers want to boost their fleet fuel economy averages, and removing the spare tire can lower vehicle weight by 30 pounds. (When it comes to mpg, every pound counts.)

In place of the spare tire are run-flat tires or an emergency flat-tire inflation kit (with an aerosol sealant and a compact air compressor).

Run-flat tires do provide extended mobility to get off of the road to a safe zone or allow one to limp home or drive to a local service provider for replacement. But replacements are sometimes hard to find and can be expensive.

Emergency flat-tire inflation kits are just a temporary fix and can tackle only small tread punctures. Never use one attempt to seal a sidewall puncture or cuts. Instead, call for roadside assistance. (Learn more about roadside assistance options.)

What's more, AAA says, using an inflator kit could damage to the tire pressure monitoring sensor. 

If You're Buying a Car

When you're buying a new car, find out whether it comes with a spare tire or an inflation kit. In many cases, even though a spare tire might not come with a car, it could be readily available through the dealership.

When weighing the decision of what you would prefer, remember there is the inconvenience and expense of having to buy sealant refill kits from the dealership after using the tire sealant system that came with the car to make a tire repair.

There are numerous choices in aftermarket sealant systems. Look for products that claim to be safe for the tire pressure monitoring system (TPMS) and/or are water soluble, as they will be easier for the repair shop to clean up, potentially reducing the cost for the inevitable professional repair. Also, check the directions for storage, as some cannot withstand the high temperatures inside a car in summer. (Read “Convenient Tire Sealants to Fix a Flat Tire.”)

Car Owner To-Do List

All tires lose pressure over time, which is why we recommend including your spare as part of a monthly tire pressure check. If it's been awhile since you checked the spare tire, chances are it is low or even flat. (See our tire pressure gauge buying guide and Ratings.)

  • If you drive an SUV, minivan, or pickup with the spare stored under the vehicle, check to make sure any nuts, bolts, brackets, or chains holding it can be loosened, and that you can get the spare out. Penetrating oil can help with stubborn fasteners. Even if the spare is in the trunk, the related hardware used to secure it can be subject to corrosion. Check all fasteners, and pull the tire out to clean any debris or dampness underneath it.
  • Don't forget to check your jack to make sure it is functioning properly, and make sure you have all the pieces and parts you need to use it, along with a lug wrench.
  • If you've never changed a tire on your present vehicle, consider a dry run in your driveway or other safe place to ensure you're comfortable doing it and have all the necessary components. Consult your vehicle owner's manual for tire care and instructions for safely changing a tire.
  • If you have an older vehicle, you should replace tires—even an unused spare tire—after 10 years or sooner, depending on what the vehicle owner’s manual recommends. To check how old a tire is, look for the tire identification code one or both sidewalls of the tire. It will start with DOT and end with four numbers; the first two are the week and the last two are the year of manufactures. So a 2314 code for example, would mean the 23rd week of 2014.
  • If you have a tire inflator kit, check its expiration date. Kits typically need replacement every four to eight years.