Please Note: Do not use this procedure if you are not certain that you can complete it safely, or if it does not seem accurate. Skippity Whistles provides this information as advice, and cannot accept any liability from your usage of it.
If your car has anti-lock brakes, chances are high you’re going to see that little Low Tire-Pressure Warning light on your dashboard.
The anti-lock brakes constantly measure how fast each tire is turning in relation to the other three. If it discovers that one tire is consistently turning more slowly, it assumes that more surface area of the tire is hitting the road, because it’s lost air pressure.
It’s there to alert you to a potential emergency. But, the light will come on even if a tire is only a few pounds lower than everybody else.
Take This Warning Light Seriously
Never ignore this light. If it comes on, pull off the road as soon as convenient and take a look at your tires. If one has gone flat, you’ll need to either change it – we have a video called How to Change a Flat Tire that shows you how easy that is, or call for assistance.
If the tire is not flat, chances are you won’t be able to tell which tire is lower. Here’s what you do.
Check Your Tire Pressure
The next time you get gas, look around the station for the Air/Water stand – all gas stations are required by law to have one. The one you find will ask you for a bunch of quarters to run the air compressor. Don’t pay it.
Instead, duck into the office and ask the cashier to turn on the compressor. The gas station is required by law to provide free air and water. They collect quarters from people who don’t know that.
Now, this is easy and kind of fun. The Air/Water stand will have two hoses, one with a water valve and one with a narrower, longer fitting on the end. The fitting is an air pressure gauge.
Put your car in park, set the parking brake, and turn it off. This will take a couple of minutes.
Drag the air hose around to the left front tire. Look around the edge of the rim – you’ll find a black tube about the size of half your pinky finger with a little cap on it. Unscrew the cap, and you’ll expose the air valve.
Although the air pressure gauges are made by different manufacturers, they all work the same. On end has a black disk surrounding a little metal post. When you push the disk against your tire valve, the post pushes the valve open and releases a little bit of air.
The other end of the gauge is a pressure meter, which immediately shows you how much air is in the tire, expressed in pounds, and reflecting the pounds per square inch, or PSI.
Take the gauge to the next tire and read that one. Do the same for all four tires, remembering how much pressure is in each one. You’re looking for the tire with either the highest pressure or the lowest.
The goal is to get all four tires up to the same pressure. Three of the tires will be very close, say 32 psi, and one will be lower. That’s the tire we need to inflate. Put the little caps on the valves of the other three tires, and let’s get this one fixed.
Push the black disk on the gauge against the tire valve, and push the lever on the gauge. You might hear a little rush of air – twist the gauge around until the hissing stops, and you’ll hear air rushing into the tire. Let go of the lever and test the pounds again.
If you accidentally put too much air into the tire, gently push the black disk against the tire valve to let some air out, and test it again.
When you get all four tires within a pound or two of each other, let the black air hose retract back into the Air/Water stand, and put the little cap onto the tire valve.
You’ll want to wash your hands, but, other than that, you did it! Congratulations.
Now, further down the road, the light may come on again. If it does, check that one tire first, rather than the other three. You may have a slow leak in it. If you do, visit a tire shop and they’ll fix it for you.