Common Causes of Rapid Tire Pressure Drops

If you happen to live in Kansas City, you know extreme drops in temperature can make your Tire
Pressure Monitoring System (TPMS) light go off, indicating your tires need air. For every 10-degree drop in
outside temperature, your tires can lose up to 2 PSI. Heat can do the opposite, raising your tire pressure by up
to 2 PSI for every 10 degrees. But what other reasons are there for your car TPMS to go off suddenly? Here are
some common causes of tire pressure changes.

Bad Valve Stem

Tire valves can weaken over time—typically several years when taking into account road
salt and chemicals. These valve stems will develop thin or brittle areas that can cause slow tire pressure
leaks. Unlike other causes for tire PSI drops, bad air-fill valves usually present in all four tires, making it
an easier problem to diagnose. If this happens, your best course of action is to purchase new tires.

Preventative maintenance, which includes regular cleaning and seasonal care, can extend the
life of your tires and air valves.

Valve Caps Missing

Without a valve cap, your tire will be more apt to lose air slowly—sometimes only 2 PSI per
month, without any fluctuations in outside temperature. Check your tires to see if any of your air-fill caps are
MIA. If so, don’t blame raccoons for stealing them; go to an auto parts store and buy a new set for a few bucks.

Corrosion of Wheel Bead Seat

Your tire is attached to a wheel—obviously. That wheel has several features, one of
which is the “tire bead seat.” The wheel or tire bead seat sits directly below the wheel flange (side ring) and
above the tire well. Beads are the first point of contact between the tire and the wheel, essentially. The
purpose of a tire bead is twofold: first, it can help increase brake clearance, and second, it prevents tire air
loss.

Therefore, if you have an old wheel or one that’s built with diecast metals, which are
prone to rust, you may have tire air leaks caused by corrosion. A small gap between the metal wheel bead/flange
and your tire can slowly deflate said tire, resulting in TPMS alerts.

The best solution is to replace your wheels, though you can sometimes utilize bead sealant and
a “buzzy wheel” to remove corroded material on your wheel bead. This should be done by a qualified technician or
at a service center or auto body shop
near you.

Poor Seal on Tire Bead

Similarly, you may have an issue with the sealant around your tire bead. This can be
caused by deteriorated rubber, improper installation, corroded or rusted wheels, a bent rim, or debris that’s
become lodged in between the seal.

Visual signs of a poor tire seal include “bead chunking”—small, raised pimples or
missing portions of rubber along the ridge where the tire and wheel meet—and “bead chafing”—obvious and overly
aggressive wear on the part of the tire that sits on the flange. A chafed tire bead is usually diagnosed by a
technician after removing the tire from the wheel.

Broken tire beads can also occur when the tire is mounted improperly or on an
improperly sized wheel, or when it’s installed on an old or dirty wheel.

New tires are the safest solution, and regular wheel alignments can help identify these issues before they become
dangerous.

Tread Puncture

Broken glass (e.g. a glass bottle) won’t usually cause any significant damage to your
tires, but there are some nasties on the road that can puncture the sidewall or tread (e.g. the 10-inch nail
that guttering company left in your driveway). This usually results in an immediate flat tire, but some smaller
foreign objects can embed into your tire tread just tightly enough to keep it inflated—until it isn’t. A small
bump can dislodge the item and cause air loss. If driven on that tire for too long, you may even start seeing
tread separation, which is a particularly dangerous condition that will literally separate the tread from the
tire—and that’s incredibly bad.

For small punctures to the tread, if caught early enough, a tire plug or patch may be a
possible solution. However, tire repairs like these are usually short-lived, and the best course of action is to
purchase a new one. Speak with your mechanic or someone at a trusted autobody center for an assessment.

Pothole Damage

Potholes are the biggest jerks in the world. Tire damage caused by potholes can
certainly result in overnight PSI drops. If you notice a deflated tire and drive on gnarly roads regularly,
potholes should be suspect no. 1. Hitting pothole after pothole will stretch tire sidewalls enough to force the
tiniest pffts of air out over time, but the real damage comes from bent rims that leave gaps between the wheel
and tire beads.

You can prevent most pothole-related PSI loss by keeping your tires properly inflated. Check
the air pressure monthly and at the start and end of each season, and fill ’em up as needed.

Bad TPMS Sensors

You checked the pressure on all four of your tires. You reset your TPMS. You had a
professional do an inspection. You rinsed and repeated. Still, after all that, you’re still getting a warning
that your tire pressure is incorrect. In this case, the culprit may be a faulty or damaged sensor within the
tire pressure monitoring system itself. Bring it to a certified dealer for assistance. They may recommend
replacing it with a new TPMS kit.

To avoid an accident—and a visit to our Kansas City body shops—it’s important to have a good
set of tires. If you notice air loss in one or more of your tires, that’s the first sign that there’s something
afoot. Get it diagnosed! For a free quote
on body work or to schedule a wheel alignment in Kansas City, contact McCarthy Collision Centers at
800-NEW-AGAIN. We’ll help you out.