Where is My Spare Tire?
By Jack Bulko, AutoAid
“Where is my spare tire?” a customer recently asked me. “And what am I supposed to do with this spray can?” I knew she was asking out of total disbelief that her new car came without a full-size spare or run-flat (donut) at all, and instead included a can of tire quick fix. That’s why I always recommend that when you purchase or lease a new car or are driving an unfamiliar vehicle such as a rental car, always check the trunk area to see what is in it. This helps eliminate any surprises on the road.
Newer cars are missing what many consider an essential component—a spare tire. Cars used to come with a full-size tire in the trunk. While a few still do, including Mercedes Benz, most spares can be found in various truck models. One of the reasons for the change was the government’s insistence on improved fuel economy.
To address this, car manufacturers created run-flat tires or donuts, which also have a smaller spare tire storage area, in the trunk. This means that even if you wanted to, you could not fit a typical full-size tire in that base. Donuts are designed for short-term use. They are reliable up to 70 miles of wear and tear. When driving with one on your vehicle, it is suggested to maintain a speed limit of less than 50 miles per hour.
Additionally, because the donut is not the same size as your other three tires, it could affect your turning radius and braking capabilities, as well as your differential (the mechanism that drives the wheels and allows them to rotate at different speeds). Damage to your differential will likely cost you more than purchasing a new tire, so please don’t wait to have a proper size tire installed.
Then there are the not-so-lucky car owners like my client who receive the can of tire sealant. Not having to include a run-flat tire means no tools or jack is needed to change the tire, which translates into less weight and supposedly better fuel economy. The main issue is that the sealant is meant to repair minor punctures and is of no use to slits in the sidewall or larger punctures in the tread.
Realizing the issues around not having a spare tire has prompted manufacturers to install tire pressure monitoring systems (TPMS) 
that warn the driver when a slow leak begins, giving the car owner time to have the tire assessed and fixed.
My Tire is Flat, Now What?
While you may save on fuel, the flip side is more aggravation for you as the car owner. If you have a full-size tire or donut you have the option of changing it yourself (but beware of oncoming traffic), contacting a roadside assistance service such as AAA or a towing service who can change it for you on the spot, or calling us at Autoaid. We offer towing services that will bring your car right to our door so we can fix it for you in our tire shop. And, if it happens after hours, we can have your vehicle towed to our repair shop. Just drop your keys in the overhead door key slot and we will address it in the morning.
There’s not a lot you can do about what the car manufacturers do or do not put into your car, but you can be more vigilant on checking your tires. Tires are typically considered to be worn if they are down to a 2/32” of remaining tread depth, however it is best not to wait until it reaches this point and replace you tires when they still have 4/32 inch tread. At that measurement, they are still within safety limits but are wearing down.
How can you judge such a miniscule amount? By doing the penny or quarter test on your tires. It’s simple: take a penny and place it upside down (Lincoln’s head down) in the tread of your tire, with Lincoln’s face toward you. If you can see the top of Lincoln’s head, your tire needs replacement immediately. However, if you can’t see the hair, you may still have some driving time on it. The quarter test is similar to the penny test. Insert a quarter in the groove of the tread. Washington’s image, like Lincoln’s, is head down, facing you. If the tread touches Washington’s head you have at leave 4/32 inch of tread remaining.
If you don’t have a full-spare or a donut in your car’s spare tire storage area, check your tire pressure regularly and pay attention to the tire pressure monitoring system in your car. If you’re unsure how to put more air in your tires or how much pressure is needed, stop by our full-service repair shop in downtown Van Nuys and let us check it out for you.
AutoAid is an award-winning automotive repair shop. Our master ASE certified technicians can fix most mechanical and electrical issues to make sure your car is safe and road worthy.
We can be reached at (818) 305-6632, Monday through Friday, and via email through the appointments page on our website. We’ll even answer your general questions. Ask us about our nationwide auto warranty that travels with you.