So you have a car that has a tire pressure monitoring system, or TPMS as we refer to them. And you think you can take your trusty tire pressure gauge and toss it in the trash. Not so. 

See TPMS only warns you if a tire is dangerously low on pressure. It doesn’t tell you the ideal pressure in most cases. So the only way to make sure you get proper tire life and gas mileage and all the things that go along with tire pressure you need to check manually at least once a month.

Alright, a couple of things about tire pressure monitoring systems there a couple of types. One is indirect reading and it reads off of the wheel speed sensors for the ABS system. They’re o.k.

The others are direct reading systems and they have a sensor in each wheel that tells the car’s computer the pressure inside each one of those tires. And within those direct reading systems there are two types. One is right here this is held on by this giant clamp those goes all the way around the inside of the wheel. Not all that popular. The others replace the valve stem. The sensor’s inside the wheel, the valve stem is out so you can check tire pressure and add and delete as needed. 

Now some of the things we see with theses, well we see lots of weird things were people hit curbs and stuff like that or technicians who don’t realize they’re dealing with a TPMS sensor and yank it right out of the sensor and stuff like that, really weird stuff. Have to use a little common sense with these things. But one of the more frequent things that we see is people who want decorative valve stem caps, and they go out and buy this gorgeous set of metal caps, they put it on to the stem and a little while later they go to take it off and the whole end of this valve stem falls off, turns to dust, and that’s because of electrolysis.

So there’s two things. Number 1, don’t use metal caps on these aluminum valve stems, use plastic caps. Number 2, use dielectric grease to grease whatever cap you out on there to help prevent corrosion and make it so it’ll come off easily. So even though it’s a passive system, there’s still some things you need to do in order to keep yourself safe. And if you have a question, or a comment, drop me a line. Right here, at MotorWeek.