Not all tire valve stems are the same size, but they do generally fall into one of two categories: “standard” and “shorty.” The standard stem is more common on passenger cars and light trucks, while the shorty stem is often found on heavy-duty trucks, trailers, and motorcycles.
The diameter of the valve stem is important because it determines how much air can flow in or out of the tire at a given time. A larger diameter allows more air to pass through, while a smaller diameter slows down the air flow.
In addition to this basic difference in size between standard and shorty stems (with “short” being a relative term), valve stems also come in different lengths to accommodate different rim sizes.
For example, some tires have a deep rim profile with lots of space for long stems, whereas other rims are flush against the side wall of the tire (this is known as a “zero offset” rim). If you need to replace your valve stem with one that has a different length than what you currently have installed on your vehicle’s wheels, you may need an adapter kit so that it fits properly.
Valve stems also come in different colors! Some people prefer black valves for their classic look; others want silver because they go with everything; still others want bright red valves to make their vehicle stand out from all others!
Shrader valve stems are more common.
In the vast majority of cases, you’ll have a Schrader valve stem. This is the type of stem you’re most familiar with if you own a car, truck or motorcycle. The Schrader valve stem was invented by August Schrader in 1891—you might hear it called an “American valve.”
This type of tire valve comes in several sizes, but the standard size for cars is 8 mm wide at the base and 40 mm long. The length includes the threaded area that screws on to your rim, which is 14 to 15 mm long. If you’re buying a new tire and want to use a different type of valve than what came installed from the factory, be sure to purchase one that has the correct dimensions for your particular vehicle.
Presta valve stems are better for bicycles.
The Presta valve stems are much narrower than the Schrader, coming in at 6mm compared to 8.5mm. A narrower valve stem is better for bicycles because it allows you to have higher air pressure without having to worry about the weight of a tire bulging out from the rim.
The pressure inside the tires is also more secure because the valve stem doesn’t stick out as far from the center of the rim, which means that it’s less susceptible to being knocked away from its closed position.
The most common size of Schrader valve is 8 mm.
The Schrader valve (often called a “car valve”) is the most common type of tire valve, and the most common size on a Schrader valve is 8 mm. The American Society for Testing Materials (ASTM) has determined that this size should be used on all passenger vehicles. However, Schrader valves can come in multiple sizes—6 mm, 10 mm and even 12 mm—though these are more rare.
In order to determine what size your car’s Schrader valve is, you need to measure it with calipers or a micrometer. To do this, simply remove the cap from your tire’s valve stem, line up one side of the calipers’ jaws against it and close them so the other side touches the opposite end of the stem. Whatever number pops up on your caliper screen determines what size your tire’s Schrader valve is.
Schrader valves differ in size from Presta valves: Presta valves usually come in only two sizes: 6 mm and 8 mm. The smaller 6 mm size tends to be used by road bikes, while 8mm Presta valves are usually seen on mountain bikes. Woods or Dunlop valves have their own unique sizing standards as well—typically 5/8” or 9/16”—but they haven’t been widely used since World War II ended in 1945; today they’re commonly only found in Asia and Africa.
It’s important to have the right tire valve stems for your application.
Let’s get one thing out of the way right away: all tire valve stems are not the same size, and they’re not one size fits all. Your car and your bike are different from each other, so it makes sense that their valve stems would be different.
The most common type of valve stem for cars is the Schrader valve, which is what you see at gas stations when you fill up. You might recognize the Schrader valve because of its black cap, which people often call a “threaded dust cap” or “tire pressure cap.” These caps can vary in style and color but they all fit snugly over the top of a standard Schrader-style tire valve stem.
If you’re looking for an aftermarket wheel for your car, make sure it comes with a Schrader-style tire valve stem before making your purchase. When you change rims on your car, it’s important to have the right tire valve stem for your application.