What Does TPMS Mean On a Car?

A lot of car owners have no idea what TPMS means. At least, they don’t know what it means until the TPMS light comes on in their car all of a sudden. 

Fortunately, this alert light is one that is not used very often. Not every car will even have a TPMS light or the corresponding alert system. However, they are getting more common in newer vehicle models and are considered luxury features becoming more and more standard. 

TPMS stands for Tire Pressure Monitoring System. Chances are if your TPMS light is on, it's letting you know that the pressure on one or more of your tires has gotten a little too low. Some systems will also alert you if the tire pressure is too high, which is most common right after you’ve filled your tires or after a significant temperature swing makes everything warmer. 

What Does the TPMS System Do?

The primary responsibility of the TPMS system is to check on the pressure in each tire and report on changes. Most TMPS systems will have an acceptable range in pressure, based on the different pressure ratings of common tires for your vehicle. Since there usually aren’t too many differences in preferred tire pressure, the range is relatively minimal. 

TPMS systems typically offer the fastest response time to changes in tire pressure. They can alert you to the problem long before you’d be able to see a visible difference in tire pressure. TPMS lights will also typically detect a tire pressure problem before the pressure is causing a significant change in your car’s driving performance. This is the reason why most people notice a TPMS light before they realize they need to check their tires. 

That isn’t universally true, some skilled drivers who are very familiar with their cars will be able to tell the difference, but most will not. 

Modern TPMS systems will detect low and high pressure since both are potentially damaging to your tires and the rest of your suspension system and drivetrain. 

Some TPMS lights will just have a single light that indicates when one of the tires is off pressure. However, more advanced and more modern TPMS lights will also indicate which tire needs your attention. Knowing which kind of system you have will make it easier to find and resolve tire pressure problems. 

Why is Tire Pressure So Important?

Tire pressure might not seem like a huge deal, especially since your tire pressure will naturally fluctuate with changes in the weather and temperature outside. Even so, tire pressure is more important than most people think. Even relatively small changes in tire pressure can cause significant changes in how your car operates. It can even make a substantial impact on your vehicle’s safety and driving performance. 

Fuel Efficiency

One of the first things tire pressure can impact is the fuel efficiency of your car. Even relatively small changes in tire pressure can change the way the tire interacts with the road. Since tire pressure usually goes down, not up, it’s more common for tire pressure problems to mean that your tires are creating greater friction with the road while you’re driving. 

The lower your tire pressure gets, the worse your fuel performance will likely be. It’s not uncommon for your tires to lose air pressure over time and lose pressure evenly across tires, especially if you have to go up and down in elevation or frequently take long drives. 

When tire pressure goes down evenly, fuel efficiency will usually go down with it at an even rate. However, when only one or two of your tires are starting to lose air pressure, you’ll probably have other symptoms of low pressure first. 

Reduced Turning Performance

Lowered handling performance usually occurs when only one or two of your tires have low or high pressure, especially when two tires are on the same side of the vehicle. 

This happens because of both low and high-pressure and changes how much of the tire contacts the asphalt. If you’re turning toward a tire will low pressure, for instance, the tire will typically slump into the asphalt more than usual. If you’re turning away from a tire with low pressure, it can also cause problems. The tire won’t lift off the asphalt as expected because its typical bounce and resistance will be reduced. 

How to Check Tire Pressure On Your Own

If your car doesn't have a TPMS system, or your TPMS system can't tell you which tire is having a problem, you'll need to know how to check your tire pressure on your own. Checking tire pressure is also an excellent habit to get into as part of regular maintenance, especially if you do a lot of your car maintenance at home. Most mechanics will check tire pressure while performing other maintenance, but if you're doing your own maintenance, you'll need to make adjustments yourself. 

Before you can check your tire pressure, you’ll need to get a tire pressure gauge. These gauges are easy to find and are typically very affordable. You should be able to get one from your local auto parts store. Even gas station convenience stores sometimes carry these useful tools. 

It’s essential to make sure you only test tire pressure when your tires are ‘cold’. That means that you should either check your tire pressure before driving or at least three hours after a drive. That's because your tires produce heat from friction while driving, which can slightly increase the internal tire pressure. Tires are designed to handle that fluctuation, but their ideal pressure range is calibrated for 'cold' pressure. If you check it while the air inside the tires is experiencing heat expansion, it will usually look like you have too much air in your tires and make you lower your air pressure when you don’t need to. 

Most gauges are designed to be inserted into the air valve stem on the tire to test your tire’s pressure properly. Digital gauges will give you a readout of the internal pressure on a screen. More affordable pencil' gauges will have a small section usually in the back that pops out with a number printed for the exact pressure reading. 

Once you have the tire pressure, you can adjust as needed. Most household air compressors are strong enough to fill a tire at home, or you can take your car to a gas station with an air pump to fill your tires there.