What Should The Air Pressure of My Spare Tire Be?

There is nothing more frustrating than getting a flat tire while you are traveling.  If you are one of the lucky ones that have a spare tire included in your car there are a few things you should know.

First off, you will notice that it is most likely considerably smaller than the normal size tires that you have on your vehicle.  This is called a donut tire and it is a temporary solution. So, what should the air pressure of your spare tire be?

The air pressure or PSI of a donut spare tire is 60 PSI. If you have a full-size spare, the air pressure should be the recommended pressure on the side of the tire; typically between 32 and 38 PSI.

If you are looking for an easy-to-read and accurate tire pressure gauge try the ProReady Digital Tire Pressure Gauge; which you can buy here from Amazon. Its compact and lightweight design makes it an ideal pressure gauge to keep in your glove box.

These tires are for emergency situations and need to be cared for just like the tires you run every day.

We will look at how often you should check the air pressure in your spare tire. How fast you can go on a spare tire and how many miles you can put on a spare tire. 

PLEASE READ: What to Do When You Have a Flat Tire for a complete guide on what to do if you indeed get a flat tire.

How often Should I Check the Air Pressure in my Spare Tire?

While we recommend checking the air pressure in your tires once a month, over here.  How often should you check the air pressure in your spare tire?  

How do you Check the Air in Your Spare Tire?

Good job, you are doing what you are supposed to do.  Check the air in your spare tire. Sooo, how do you go about doing this?

Checking the air in your spare tire is just like checking the air in your regular tires.  Use a tire pressure gauge to measure the air pressure in your tires.

• To recap, find the valve stem on your spare tire.
• Unscrew the cap
• Press the air pressure gauge against the valve stem and get the spare tire air pressure

For more complete instructions click here

The biggest trick is going to be GETTING to your spare tire.

First, you have to locate where your spare tire is at. (This is best done at home, under controlled circumstances)

In a four-door sedan, the spare is most likely buried in the trunk.  So all the stuff you have stored in there needs to come out first.

In a truck or minivan, it is most likely underneath the chassis. And it needs to be lowered with a special tool.

Once you find the spare and get access to it, follow the steps above to check the air pressure.  

Why do Spare Tires have a higher PSI?

Now you know how to put into your donut spare tire, but how much air do you put in?  Well, if you look at the sidewall, it’s going to tell you 60 PSI.

Why is the air pressure in a donut spare nearly double of that in a full-size tire? According to TireRack, donut spares have a higher air pressure because of their smaller dimensions.

That’s right, a donut spare has about half the contact surface of a full-size tire.  To compensate for the reduced surface area, the air pressure in the tires needs to be higher than a full-sized tire.

What Should the Air Pressure be in a Full-Sized Spare?

If you are lucky enough to have a full-size spare, at what air pressure do you keep that tire.  There are actually three types of full-size spares; let’s look at each one.

Matching Full Size Spare

A matching full-size spare is just like the tires you are using on your vehicle.  These should be inflated with the same air pressure as your running tires.

In fact, they should be incorporated in with the tire rotation, so that they wear out evenly along with your regular tires.  

I was able to run my matching full-size spare for several weeks before I replaced my tire.

Mis-matching full size

This is a normal tire, however, it does not match the tread pattern or may not match the size of your running tires.

Nevertheless, these are normal running tires and should have the same air pressure as your regular tires.

These are still temporary and should be replaced by a matching tire as soon as possible.

Full-size Temporary

These tires have the diameter of a full-size tire, but the profile of a donut spare.  Follow the manufacturer’s recommended air pressure for these types of tires.

You can find this information in the owner’s manual or the sidewall of the tire.

Final Thoughts

There you have it.  Spare tires are easy to forget about, but they need to be maintained like any other tire. After all, a flat spare won’t do you any good in an emergency situation.

Next time you are performing maintenance on your tires, don’t forget to check the spare.

Safe travels…

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References:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=141

https://www.doityourself.com/stry/5-facts-about-spare-tires