3 common Reasons Why Do Spare Tires Have Higher PSI

One of the most frustrating moments for car drivers is seeing the tire getting punctured. At this moment, a spare tire can be a lifesaver for you. You can quickly replace the punctured ones with a spare tire at the back of your car.

However, many people get confused seeing spare tires with higher PSI than their original car tires. So, why do spare tires have higher PSI than the original ones? Is it wrong to mount a car tire with higher PSI than the actual one?

Well, the answer lies in the size of your spare tire. Spare tires are slightly smaller, with less contact space with the ground. Car manufacturers purposefully make the spare tire smaller to place it inside the tight back space of the car. With the smaller size, it has less contact surface with the ground. Thus, it can accommodate much less air. As a result, spare tire manufacturers increase the air pressure (PSI) level to maintain the standard.

Why Do Spare Tires Have Higher PSI

Why Do Spare Tires Have Higher PSI?

Car tires mostly have 30PSI to 35PSI air pressure levels. On the contrary, spare tires such as Donut Tires have 60PSI air pressure. As you see, the spare tires have 2X more air pressure than the original ones installed in the vehicle wheel.

So, why is the pressure of spare tires so high?

  1. A spare tire is small, so its increased pressure helps maintain the driving balance.
  2. Manufacturers input higher PSI for the spare tire as it remains unused for a longer period to lose air in the long run.

The two points may be complex for you to understand. Thus, we will elaborate on it.

1. Smaller Tire Size Requires More Air Pressure:

The answer lies in their dimension. Most spare tires, such as Donuts, have smaller sizes. Manufacturers make the spare tires smaller so that they can fit in the tight backspace of the automobile. As the dimension of the tire reduces, its contact surface with the ground decreases too. The spare tires are a drawback as less contact with the ground means the vehicle will be imbalanced.

Therefore, spare tires have increased air pressure levels to counter the imbalance caused by their size. However, its higher PSI means the tire will still put the same pressure on the ground with the compact size as it would with a full-sized tire.

2. Unused Spare Tires Lose Air Pressure:

Also, the spare tires remain unused for an extended period. These items will remain unused in the back of your car for months and even years. During this period, it loses a bit of the air from its inside. So, the manufacturers increase the air pressure of the tire. It ensures that even if the tire loses some of its air and air pressure, it remains at the standard level for the vehicle.

If the spare tire comes with the same pressure as the original one, it won’t remain usable after a couple of months. Since it will lose air pressure over time, its PSI level will drop even below the original tires after a few months. To counter this problem, spare tires have 2X more air pressure.

This way pare tire maintains the perfect balance for the wheels with the original ones. So, you won’t have any problem driving the car.

What Is The Standard Air Pressure For Spare Tires?

Compact tires are smaller, so they require more air pressure per square inch. Therefore, a spare or compact tire must have a 60PSI level to maintain the balance among all four wheels. Also, a minimum of 60PSI pressure is necessary so that the tire maintains proper contact with the ground. Therefore, it will improve your driving experience significantly.

If the spare tire has less air pressure, it could damage the wheel and cause fatal accidents. On top of it, your driving imbalance will be a worse experience. So, you should inflate the spare tire with at least 60PSI.

Also, PSI level is linked with the fuel consumption of your car. 

A temporary fix guide:

As you install the spare tire with 60PSI, you will still need to inflate, fix and remount the original tire on the wheel ASAP. It is useful because you can use a spare tire only for 100 miles at 55MPH speed. The tire can burst anytime if you drive the car at a higher speed. Also, its thinner outer polymer cover won’t survive the harshness of the road for more than 100 miles.

Thus, you must find an automobile repair shop and fix the genuine tire ASAP. It will help you maintain the car better too.

Tips on Checking and Maintaining PSI Level of Spare Tire:

You must maintain the proper PSI level when installing the spare tire on the wheel. For this, you should bear an air pressure gauge in your car. These days, many digital pressure gauges let you quickly measure the actual PSI of the tire.

If the tire lacks a proper PSI level, you must inflate it accurately. You can carry a compact air compressor in the back of your automobile. It will ease your spare tire maintenance.

people also ask (FAQs)

How long can I use a spare tire?

A spare tire is a temporary fix. You can only use it for 100 miles to drive the car. So, you must replace it ASAP.

At what speed can I drive my car with a spare tire?

With a spare tire, your automobile driving experience is limited to 55MPH. However, experts suggest maintaining the speed level below 50MPH.

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You should now clearly understand why spare tires have higher PSI levels. As it is compact and holds less air, the manufacturers increase the air pressure for safety concerns. Maintaining the right balance between all four wheels of the car is essential.

So, always check that the spare tire has a 60PSI level when installing with the car wheel.

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Mahir Ahmed


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