Why does the air pressure in motorcycle tires drop?

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It’s probably safe to say that most of us motorcycle riders have occasionally been caught in a situation where we find ourselves with low tire pressure. And it’s usually at the least convenient time, too.

A motorcycle tire can lose its air pressure for a variety of reasons. Because of this, it can often leave a motorcyclist frustrated since it’s usually not obvious as to why it’s happening.

Why does motorcycle tire lose air pressure? Changes in temperature can cause motorcycle tires to lose more air pressure. A faulty valve, bent rims, worn tires, cracks or bald spots, and even a tiny hole punched through the tire can all cause motorcycle tires to lose air pressure.

It’s discouraging having to deal with a low pressure tire on a motorcycle, especially if it keeps happening and you don’t know why. I’ve had my fair share of tires that mysteriously get low on pressure and this article will explain everything I’ve learned as to why it happens and what you should do about it.

Why Motorcycle Tires Lose Pressure

The most important part of a motorcycle is its tires. They’re basically the only thing that’s between you and the road. Yet a lot of riders don’t pay much attention to them unless they’re causing some sort of trouble.

Sometimes low tire pressure isn’t always obvious and most motorcycles don’t come with a tire pressure light on their instrument panel. Other times, it’s completely obvious either by the way the tire looks or by the way the motorcycle is handling on the road. It doesn’t matter what your situation is, it is vital to have the correct tire pressure.

Temperature changes outside are the first and most common cause of a motorcycle’s tire losing pressure. Generally, a motorcycle tire loses about 1 PSI for every 10° drop in outside temperatures. That may not seem very significant, but when you go from summer to winter where it’s about a 70° difference, that means your tire is about 7 pounds too low.

However, motorcycle tires can lose their pressure if they are exposed to too much heat. The pressure inside your tire will expand if it is too full and you leave it outside during the summer heat.

While not as widespread, A faulty valve could also cause a motorcycle’s tire to lose its pressure. It could be because it is not connected correctly to the tube canal, which would likely be a manufacturer issue, or because the pin at the top got bent permanently. This would allow air to flow out continuously. That’s why it’s important to always have a cap on the valve.

There are two types of motorcycle tires. There are a lot of motorcycles nowadays that have tubeless tires which means the tire you see is what’s actually holding in the air. This is because it suctions to the rim it’s around. A bent rim can easily cause the tire to lose air pressure because the tire isn’t able to suction to the rim properly. This can happen even in the smallest of bends due to potholes and other road obstructions.

There’s a reason motorcycle tires have a life expectancy; too worn of tires aren’t safe for the rider because they’re no longer reliable and don’t have any traction. A worn out tire, or a tire with an obvious bald spot, can cause a motorcycle to lose tire pressure because it’s extremely susceptible to forming holes. You should replace tires that have become worn quickly.

It’s also possible that a hole was punched through the tire at some point while out for a ride. Because rubber tires for motorcycles are tough, they can withstand most road debris. Holes are often caused by things like nails. Check your tires for nails and other debris.

What is the Normal Tire Pressure Loss?

Each motorcycle tire loses pressure over time. That’s simply how tires function. Knowing the difference between normal air pressure loss and what’s considered too much may help you be a bit safer out on the road.

A motorcycle tire naturally loses some of it’s air pressure because of a process called osmosis (also known as permeation). This means that air can pass through rubber particles in the tire at certain points, much like how helium and oxygen escape a balloon over time.

Different makes and models require different types of tires. Average tire pressure loss on motorcycles is about 1 to 3 PSI per month. This is why it’s important to regularly check your tire pressure to ensure you keep up with the natural occurrence of osmosis.

As it was stated previously, it’s completely normal to lose about 1 PSI of pressure in your tire for every 10° drop in the outside temperature. That’s often why a lot of car and motorcycle owners end up filling their tires in the fall or winter because of the dramatic temperature change. The pressure drops because the temperature drops and the air molecules in the tire condense.

If you live in an area with warm days and cool nights, it’s normal to see lower tire pressure at night then have a normal pressure during the day when the temperatures rise again.

What happens when you ride with low tire pressure

Riding a motorcycle with low tire pressure is not only uncomfortable, but it’s also dangerous. Low pressure on either the front, rear, or both tires can make it dangerous.

Low tire pressure will result in more tire contact with the road, which eventually causes friction between them. This can cause premature tire wear and even tread separation.

A motorcycle engine has to work harder when it doesn’t have the proper tire pressure. A lower pressure means that the motorcycle must work with more, and the engine will compensate by increasing the pressure. It could ultimately affect your gas mileage or even cause it to drop.

It’s also more difficult navigating a motorcycle with low tire pressure. A motorcycle with less control means that you are more likely to get into an accident.

You could damage the tires if you ride a motorcycle that has very low tire pressure. The lack of air provides minimal protection between the metal road rim and the road. Any bump or hole could cause a dent. It is very difficult to repair motorcycle rims. You can read my article to learn more about how to repair motorcycle rims.

How to check for air leaks

If you suspect you have a tire pressure air leak on your motorcycle that isn’t due to natural temperature changes or osmosis, you should inspect your tire to locate the leak. If you have a tubeless tire, there are a few simple ways you can check to see if you have a slow leak somewhere you’re not aware of.

Make sure you have a solution that is easy to bubble, such as soapy or water. It’s easiest to have the tire off the motorcycle but is doable if it’s still attached, you’ll just have to pay closer attention. Combine the soap and water in a spray bottle. Let it sit for a few moments before spraying the soapy water onto the tire tread. Leakages will be visible as bubbling. It’s best to start at holes that were previously mended as those have a higher rate of failing after a while.

It is important to check the valve and the area around the tire’s rim, where it touches the metal. This will help indicate if a bent rim is the problem; similarly, a faulty valve will also bubble if there’s a leak coming from there.

Many tire repair tools are available that can be used to puncture larger holes than the original, and then plug it. Although it might seem tempting, I recommend taking the motorcycle tire to a tire shop so they can repair it correctly. That’s a fix you don’t want to get wrong.

It can be difficult to find a leak if you have tubed tires. It is almost impossible to find the inner tube without a tire mounting device. Simply taking your motorcycle to a tire shop will allow you to determine if it is losing too much pressure.

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