How Much Air (PSI) Should Spare Tire Have [Explained]

Having a flat tire can generally be frustrating if you are on a trip or even driving in the city. Luckily, you might be having a spare tire.

We say luckily because some new cars now do not come with spare tires. What if you go to take out your spare tire and find that it is also low on tire pressure?

We can ask such questions because not many people know the correct PSI for spare tires.

Most spare tire manufacturers recommend that the donut spare tire should have 60PSI while the full-size spare tire can have what the other tires are having which will be 35PSI in most cases.

Types of Spare Tires

1. Donut spare tires

Donut or compact spare tires will be the most common type you find in various cars right now.

The manufacturers switched to compact spare tires simply because it could allow them to reduce the car weight and fit a tire in tight spaces.

Just because it is a compact spare tire, expect it also to vary based on the size of the vehicle. It is not hard to miss it because it would have narrower width and its wheel would be either black or yellow.

Once you have mounted this spare tire, make sure you drive straight to an auto shop to get the normal tire repaired. You are not supposed to keep driving with a spare tire for too long.

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So, what are the recommended driving distance and speed limitations?

Once you have the donut tire mounted on the car, consider driving it for no more than 50 miles. It is expected that you should have found a tire shop within 50 miles.

As for speed, you should not exceed 50 mph. This is good enough to get you to where you can find a proper service center to work on your tires.

Driving too fast or past the recommended distance can generally put more pressure on the tire and may lead to premature wear and potentially break the tire too leaving you even more stranded.

1. Drive control issues

Because of the compactness, it is possible that you may experience some control issues. That is why you are advised to drive slowly until you have the normal tire fixed.

You will find that the narrow tires do not help either. This is because you now have reduced traction thus stopping and accelerating fast might not be an option.

You may also experience more stress on the car’s differential and drivetrain if you keep using such a tire for months because it does not balance with the other tire on the axle.

If you can keep the donut spare tire pressure at 60PSI, the better. It might seem high, but it is necessary to cover for the lack of tire width and hold the car’s weight better.

The donut tire has a lifespan of around 6 years. You may want to get a new tire to replace it with even if you have not used the donut tire that many times in 6 years.

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Here is a video with more information on compact spare tires

YouTube video

2. Full-size spare tires

A full-size spare tire is not as common because of how much space it takes up in the vehicle. For this reason, you might only get it if there is enough space to hold it.

The good thing is that you can have a matching spare so that when you put it on your car, it does not need replacing immediately.

Some even rotate such spares during the routine tire rotation after several thousand miles.

With a matching full-size spare, you can have the flat tire patched and it is now converted into the new spare tire.

You also sometimes get people using full-size but mismatched tires. Such spares can work well and be used for longer than compact spare tires, however, you cannot use them as part of the tire rotation routine of the car.

We recommend that once you have the flat tire fixed, mount it back and the spare goes back to storage. It is mostly best to get the full-size matched spare tire to save you trouble.

3. Full-size temporary spare tire

This one will have a full-size configuration, but the tire has shallow treads. The aim is for it to be a spare tire only. The shallow treads also help in taking up less space during storage as compared to the normal tires.

This type of tire would be matched to your vehicle specifications. As such, it does not affect components such as ABS and traction control.

The other benefit is that it would not add too much weight to the vehicle’s storage. So, you can have the right temporary tire to use until you can have the normal tire fixed.

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Here is a comparison between the full-size spare tire and donut spare tire

YouTube video

How Often to Check the Air Pressure of a Spare Tire

How Often to Check the Air Pressure of a Spare Tire

You might have been told to check your car tire pressure once or twice a month. Some might do it others not so much. Does the same rule apply to the spare tires?

Since you would not be using the spare tire more often, checking it every 6,000 miles should be enough.

For full-size tires, make sure to check the tire each time it goes into rotation. You want to ensure it is within the same PSI as the other tires on the car already.

Checking the air pressure of the spare tire is necessary as much as you would not use it more often. This is because air can leak out over time and 6,000 miles is a long time. It can be 6 months or even a year for some people.

Since modern cars have small air compressors, it might just be what you need to inflate the spare tire.

How To Prevent Having a Flat Tire

It might seem like a hustle sometimes to change the tires on the car. So, how would you end up preventing having a flat tire in the first place?

  • Keep the tires inflated

Sometimes it is user negligence that gets them a flat tire. If you can have the tires properly inflated, then it is possible to avoid having a flat. When you go to inflate the tires, make sure to do it right. Overinflating is just as bad as underinflating as it can lead to more wear to the tire.

  • Check the spare tire

You are also advised to check the spare tire more often or as recommended. You might think that just because it is not used, the air pressure does not reduce. You might be surprised that the spare tire could be defective and it is losing air for only you to discover it when you need to use it.

  • Check for uneven wear

When the tires have uneven wear it means there is a problem. This unevenness can make some tires more likely to lose pressure than others due to punctures. So, make sure the car is well aligned and balanced to discourage uneven wear. You could also consider replacing the worn tires that can be prone to blowouts.

  • Avoid driving near construction sites

Streets near construction sites are likely to be filled with objects that can puncture your tires. This includes nails, screws, glass, and more.

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Why do spare tires come with high PSI?

The high air pressure is to compensate for having small dimensions. This is key to help support the weight of the car better.

Do all new cars come with spare tires?

No. Most companies now only offer a repair kit to use in case you have a flat tire. This includes the patches and a small air compressor to keep you going.

What is the correct air pressure for spare tires?

If it is a compact or donut tire, use 60 PSI. The full-size spare tires can use the normal range of 35PSI.

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