No More Explosions: Safety Tire Pressure Monitoring Systems

Posted 1/9/23

It seems like every time the temperature drops there’s a light on your dash telling you that your tire pressure is just a little bit low. Depending on the age, make, and model of your car you may have specifics of just which tire is low, or an angry exclamation point in something resembling the cross-section of a tire telling you that something just isn’t right. And though you may go grumbling to your nearest air compressor to check on the tire pressure and top things off, what you may not realize is how important that little light—and you actually paying attention to it—may be to keeping you safe.

The Luxury of Monitoring Your Tire Pressure Automatically

At the beginning, tire pressure monitoring systems (TPMS) were a luxury feature that were only found on some of the most elite imported vehicles. It’s been well known for years that tire pressure is important to staying safe on the road, and when you’ve got a twin turbocharger under the hood, you want as much info on the status of your car as you can get. Naturally the first vehicle to get one of these monitoring systems was a perfect blend of speed and German safety engineering—a 1986 Porsche 959. The safety feature first made it over the pond into America on the 1991 Corvette model year as a $325 add on to the $32,455 base price. 

Monitoring your tire pressure is a good way to prevent a myriad of issues. Poorly inflated tires can give you poor fuel economy and tires that wear out more quickly, and can also lead to more dangerous problems like blowouts, poor handling, and longer stopping distances. And though this feature was a great way to keep people safer on the road, in the late 1980’s and 90’s it was largely considered a luxury feature on already top-of-the-line cars. But just a few years later things had changed in a big way.

Enter Ford, Firestone Tires, and Their Fatal Problem

In the mid 1990s ATX and ATX II Firestone tires were installed as standard on a number of vehicles released in the US—most notably on some Ford Explorer models released starting in 1990. These tires had been included on Ford Rangers for a number of years without incident. But the top-heavy nature of the Ford Explorer led Ford to recommend that the psi for these tires be held at 26 while installed on the Explorer models to improve ride quality and lower the center of gravity. It’s notable, however, that when these same tires were installed on Rangers, the recommended psi was 35. Though underinflated tires have been a known safety hazard for decades, this much lower inflation level for the same tires was not seen as a problem. This would become a problem.

By 1996 it was known that there was a problem with the treads separating from the rest of the tires—often in high-speed situations on highways. The lower tire pressure allowed the tires to get much warmer than they ever had when inflated to 35 psi, and if it was already a hot day, they would get even hotter still. As the tread separated, it became nearly impossible for the drivers to control the vehicles, and since the Explorer already had a high center of gravity, there were many accidents and fatalities, with over 100 deaths being attributed to failure of these tires.

The TREAD Act and America’s New Focus on Tire Safety

Because of the bungled way that the National Highway Traffic Safety Administration handled the reports of the issues with these tires—they did not even formally issue a mandatory recall for the tires until 2001—Congress passed the Transportation Recall Enhancement, Accountability and Documentation (TREAD) act that was designed to ensure consumer safety. The TREAD Act requires mandatory early reporting on any kind of manufacturing defects, including those that are identified in another country (the tires were being quietly replaced on Explorers sold in Saudi Arabia by Summer 1999) and on how to address these problems. It focuses on tire safety in general, and Section 13 lays down the groundwork for the requirement that all new vehicles have to have a tire pressure monitoring system. By 2007—a mere 21 years after the first ever TPMS—the monitoring system was a requirement on all new vehicles in the United States.

How Does Your Car Know That Your Tires are Underinflated?

There are two types of TPMS: indirect monitoring systems (iDPMS) and direct monitoring systems (dTPMS). The indirect systems (as the name may suggest) don’t directly have a tire pressure gauge that monitors the exact psi in each tire. Instead the computer uses an algorithm that analyzes the data like the wheels’ speeds and driveline data that is given by other sensors to figure out if the tire is underinflated. For example, if the computer senses that one of the tires is spinning just a little bit faster than the rest, it makes the assumption that the wheel is underinflated. An underinflated wheel has a slightly smaller diameter—and will need to spin slightly faster to go the same distance.

Most newer cars have a slightly more precise direct monitoring system (dTPMS). Instead of checking other data, a dTPMS uses a tire pressure monitoring sensor that is mounted to the tire, most often attached to the valve stem inside of the tire. Each tire has a separate sensor, and these are able to wirelessly transmit real-time data as to the inflation levels of each of your tires, no matter whether the car is moving or parked. 

Safety First: Luxury and Innovation of European Cars

Though tire pressure monitoring systems are now required to be standard on all cars sold in the U.S. these days, it’s interesting to remember that they were once only found on the most luxurious of imported cars. If you can afford the best, you will definitely be paying attention to the speed, sleek curves and luxury of your vehicle, but buying an imported car will also net you some top of the line safety features. Back up cameras are another luxury feature that are now required as a safety feature on all new cars. Who knows what luxury safety feature will become standard next?

Never Worry About Finding Local Quality Car Repair Again

When it comes to cars, you can always rely on one thing; they will always need maintenance service. And whether it is standard car maintenance like oil changes and new brakes, or something more unusual like a cracked headlight or a blown gasket, having a local Cincinnati auto repair shop in your pocket is key. It is stressful when your car isn’t running right, so do your homework in advance to find car repair service garages. Check the reviews and go in for a chat. Be choosey in advance so you have top-notch service when you need it.