plain vs. tpms vs. metal valve stem caps

I just talked about getting new tires, and it's worth talking about these little things, valve stem caps (a.k.a. valve stem covers).

There are several different types of caps out there, and they all fall into one of three categories: Plain, TPMS or metal. Which is the best?

I'll answer that question, but before I do, "plain" usually refers to short, stubby plastic caps, "TPMS" usually means plastic caps that are supposedly better for cars with a Tire Pressure Monitoring System (which is pretty much all cars since 2000, and yes, sometimes those sensors need to be replaced), and "metal" means the cap is literally made of metal (usually aluminum) instead of plastic.

Metal is the worst type of cap to use for one simple reason. It's the most difficult to grip. It doesn't matter if the cap has knurling on it or not. Over time, that cap is going to accumulate dirt and road grime. When the time comes (and it will) that you have to take off the cap to add air or even just check the tire pressure with a gauge, you'll fingers will slip on the stupid cap when trying to grip it. This means you'll have to grip the cap harder both for taking it off and putting it back on.

You will immediately notice that plastic caps have much deeper grooves on the outside. And guess what? Your fingers will find that much easier to grip and turn.

Does a plastic cap labeled as TPMS actually affect the performance of the TPMS at all? No, because the TPMS is inside the wheel. However, caps labeled as TPMS are physically longer.

Whether to use plain short stubby caps or the longer TPMS caps depends on your personal preference.

I prefer the TPMS cap and think it's the best because it's longer and easiest for my fingers to grip.

If you like the longer caps with easier grip, get TPMS caps. However, if you think the longer caps look dumb (they do stick out more, after all), get the short stubby ones instead.

What about decorative caps?

An example of a decorative valve stem cover is the dice style cap. They literally look like dice and come in white, black, red, yellow, green and blue, your choice.

Another example is the 8 ball valve stem cap, which obviously looks like an 8 ball from a pool game.

Yes, these look cool, but I wouldn't keep them on my valve stems all the time due to the extra weight and nonstandard shape. If for example you have a classic car or truck and wanted to throw on a set of these for a car show, sure, go ahead. But after the show, put regular sized caps back on.

If you want a decorative cap you can keep on the stem all the time that acts normally, luminous caps are what you want. What are they? Glow-in-the-dark caps. Standard shape, gets its charge from sunlight, glows at night. How well do they work? I have no idea, but again, it's a standard shape, so you can leave them on the stems all the time. And yes, there are caps with LEDs in them also. I've no idea how well those work either.

Can you skip the caps entirely and just leave the end of the stem uncovered?

Yes, but it's not smart for regular passenger cars, trucks and SUVs. Road grime will collect in there over time, and that means two things. First, when you use a tire pressure gauge, that grime will be sprayed directly into it, and possibly wreck the thing. Second, when you add air to the tire, it can damage your air pump and the stem itself from grime being pushed through, and possibly cause the stem to fail outright.

The caps are there to keep road grime out of the stem. Use them.

Published 2025 Apr 10