Valve Caps: What You Need To Know

A valve cap

What is a valve cap? Does it really matter if they are on the car? In order to explain what a valve cap is, we first have to explain what a tire valve is. If you know how to put air in your tire, you  know what a valve is.

There are 2 different types of valves that are put on passenger vehicles. First up we have the normal rubber valve.

a valve with a cap on it
Rubber Valve

A valve with it's cap off








These are nice because they are a pretty cheap and easy fix if they start to leak. The other type of valve is more common these days because all new vehicles manufactured after 2008 were required to be TPMS compatible.

What does TPMS stand for and what EXACTLY does it do?

TPMSwith it's cap ont
TPMS Sensor

TPMS with it's cap next to it










TPMS stands for Tire Pressure Monitoring System. TPMS electronically monitors the pressure in a vehicles tires. To get into everything that is TPMS you would have to read a whole different article which you can find if you CLICK HERE. 

When it comes to the valve caps they could be black, gray, green or even look like skulls or dice. The color/shape isn’t really important. What IS important is whether they are plastic or metal. If you have rubber valves it’s really not a huge issue but unfortunately it is a huge issue with TPMS.

The problem is that the metal valve caps can seize on the Schrader valve part of the tire valve. When it seizes it’s stuck and when it’s stuck the only way to get it off is to break it. With rubber valves it’s a cheap and easy fix. With TPMS it becomes costly because you have to pay for the sensor AND have it programmed. You can’t just take any sensor and put it in your tire. Well, TECHNICALLY you can but you vehicle will never read it and the ( ! ) light will never go out.

That’s nice an all but why do we care about that stupid little cap?

Good question! The cap is actually quite important. The cap keeps dirt and moisture out of the valve. If too much moisture and/or dirt get’s in there it can cause the valve core to size. 

What is a valve core?

A valve core is a little “check valve” that is located in the tire valve stem. Then you push is down air can flow through it allowing you to inflate/deflate tires. 

If too much moisture or dirt gets to the core it could seize in place. If they happens you can’t get new air in or excess air out. Again, if it’s a rubber valve it’s not a hassle. If it’s a TPMS sensor you have to buy a new sensor and have it programmed to your vehicle.

The core from inside of the valve
Valve Core

So if you make sure to keep those little caps on your tire valves it can potentially save you a lot of time and money. Don’t forget: Put on plastic caps and NOT metal ones.