Does the air tire valve cap on your tires fail?

There’s only one part of your vehicle that makes contact with the road surface, the tires. If the tires aren’t properly inflated, you are in danger. That’s why you take the time to ensure proper inflation and good tire health. But what happens when the valve cover on your air-tires is missing? Are tires affected by a missing air valve cap? 

When the tire valve cap goes missing, air shouldn’t be lost. Air won’t be able to seep out of the tire just because it’s missing a cap. There are purposes to having the valve cap in place, but keeping the air inside the tire isn’t a reason. 

This guide will explain the functions of the tire valve caps. It is important to know how tight the cap should be. We will also discuss the possible reasons your tire may lose air. You will find information about which valve stem caps are available and how much they cost to replace. 

What's the Air Tire Valve Cap?

The valve cap isn’t used to keep the air from leaking out of the tire. It doesn't matter if the valve cap is attached to the stem. However, it does have an important function that shouldn’t be overlooked.

The valve stem cap prevents the valve getting contaminated by debris and other goo as you drive your vehicle through water, snow, dirt and mud. The valve could be damaged if it were to become clogged with mud. If there is a lot of mud on the valve, it may be difficult to properly inflate your tires. 

Are Tire Valve Caps Broken?

The tire valve cap can sometimes fall off. If you haven’t tightened it correctly, it could fall off on its own. That’s why it’s important to secure the cap.

There’s also the chance that an impact could make it pop off. Scraping the car against the curb could cause the cap to come off. This can cause damage to the stem, and possibly leakage. 

But, misplacement is the main reason why tire valve caps can come off. When you take the caps off to fill the tire, it’s easy to misplace it. For reinstallation, make sure to secure the caps after you have filled the tires. 

Are Tire Valve Caps Universal?

The valve stem caps for most models are universal. There are many auto parts stores that can sell replacement valve stem cap for your vehicle. In fact, it’s hard to find them sold individually.

The valve stems will be slightly different if your vehicle is heavy-duty or farm equipment. It is possible that you will need to buy your valve caps at a tire store. 

What is the best way to tighten valve caps?

You want to tighten your valve caps until you can turn them. Don’t use tools on the valve caps because they should never be that tight. Overtightening them could lead to damage. 

You will need to reapply your valve cap by placing it on the stem, turning it clockwise one-half of a turn. The cap will be securely seated onto the threads by doing this. Once it is secure, you can tighten it up until it doesn’t go any further, but don’t overtighten it. 

There are many reasons why tires lose air.

1. Broken Valve Stem

While the valve cap isn’t going to cause leaking air, a defective valve will. The extent of the damage will determine how much air leaks.

It’s possible to have a minor leak that is barely noticeable. It could leak so bad that it is almost impossible to hear any air leaving. 

2. Tire Puncture

It is possible to puncture your tire by hitting anything on the road. Most common are nails, screws and other debris that is left on roads. 

Depending on how the puncture occurs, it might automatically plug the hole, so you don’t notice any air loss at first. You might be able get a plug or patch put in if the air is leaking. There are situations where the puncture can't be fixed and you will need a brand new tire. 

RELATED: Tire patches or tire plugs?

3. Broken Wheel

Hit something hard on the roads can cause damage to your rim. The wheel can be damaged by hitting a curb or running into a pothole, as well as colliding with other road hazards. If the tire can’t seat correctly on the rim, air could leak out.

Most rims that have been damaged are irreparable. To ensure road safety, you would replace the rim. 

Related: How much do rims cost?

4. Broken Bead

You will find the tire bead where rubber and wheel seal together. If the bead isn’t perfectly sealed, air can leak out.

If the bead is damaged, this can happen. You may also experience this if there is debris between the tire & wheel. This allows for air to leak out. 

5. Tires from the past

Tires will age, especially if they aren’t used. Dry rot can occur when tires sit, particularly in sunlight. 

The tire will eventually wear out, even though it has been used. Tires that become brittle will eventually separate and leak air. 

RELATED: Tire Dry Rot: Warning Signs, Replacement, Prevention & Safety

6. Temperature changes

It’s always recommended to check tire pressures when the temperatures change. That’s because the temperature outside has a profound effect on how much air is in the tire. While the fluctuation won’t cause air to seep out, it does change the density of the air pressure.

Tires lose more air pressure as temperatures fall. It is the opposite. With temperatures rising, pressures increasing in combination. It could appear that the tire may be leaking air if the temperature drops quickly. 

Some air will naturally lose from tires over time. Air molecules can change their pressure and composition which will cause a decrease in the psi. That’s why you want to check the tires monthly, at a minimum. Regular inspections will help you catch problems early so that they don't affect your safety on the road. 

Replacement of a missing tire valve cap

A large pack of tires valve caps can be purchased at your local auto parts shop for as low as $10. You might spend more if you have a large truck, or if you want something extra special. Plus, you don’t need anyone’s help to install valve stem caps, it only takes a few minutes

This is also an easy task if you have to replace the stem of a tire. You might be able to fix it yourself for around $10. If you don't have the skills to do it yourself, then expect to pay $25-50 at your local tire shop. 

Different types of Valve Stem Caps

When you go to an auto parts shop or tire shop, there are many options for valve stem caps. People tend to choose inexpensive plastic caps. These work great in normal driving conditions and won’t cause any unusual issues. These caps can be purchased in large packs to ensure you have enough for the event that one is lost.

You can also get metal dome caps. They are more durable at higher temperatures such as drag racing or operating a high-performance vehicle. Knurled metal caps make it easy to adjust or remove. There are also hex-head options. You will find a special O-ring, or other seal to keep the valve in place with the metal caps.

We don't recommend aluminum and metal tire valve cap replacements for plastics. Aluminum and metal caps may corrode or rust and can be difficult to remove without damaging your air valve stem.