How Low Can Tire Pressure Really Be When It’s Time To Drive?

by | Dec 17, 2019

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The low-tire pressure light — that pesky orange light on your dashboard always seems to come on at the worst times — when you are running late for work, stuck in traffic, or on a deserted road. 

I should know. About 2 months ago, I suffered a low tire-pressure induced blowout in the middle of the Howard Frankland Bridge in bumper to bumper traffic.

And it was pouring rain.

And blowing wind.

Oh, and there was some lightning too.

It was not ideal.

When you see the low-tire pressure light pop up you might feel concerned but usually not concerned enough to stop as soon as you can for air. Hell, you might choose to ignore that light for a few days or even weeks (er, possibly even longer if you are a true procrastinator)! I mean, you don’t have a flat tire (yet, you hope!) so it’s not a big deal driving with your low-tire pressure light is on, right?

Wrong! It might seem like a royal pain to stop and take care of your low-tire pressure but really — do the right thing and just get ‘er done. 

The longer you leave your low tire pressure, the more you set yourself up for a litany of problems including lower gas mileage all the way to a potentially catastrophic blowout!

Why is it important to check tire pressure?

Checking your tire pressure and keeping your tires properly inflated is a chore, but it is much easier than dealing with the consequences of under-inflated tires. Low tire pressure can negatively affect handling, tire wear, fuel economy, and most importantly, safety. 

Low tire pressure can also cause a car to be less responsive and have less traction, making it more difficult to avoid emergency situations (think switching lanes last minute in traffic or dodging a pothole). Less traction also means that your car’s engine will have to work harder and use more gas than it needs to. According to the EPA, properly inflated tires can increase fuel efficiency by three percent or more. That is money in your pocket!

Your fuel economy suffers when you under inflate your tires. Under inflated tires can lower your gas mileage by about 0.2% for every 1 PSI drop in average pressure.

While that might not seem like a lot at first, let’s assume your tires are under inflated by about 12 psi, which is very common. Assuming you drive the nationwide average of 13,476 miles a year, your under inflated tires are wasting roughly a full tank of gas each year.

But that isn’t all.

Under-inflation causes tires to distort, leading to increased wear, especially on the sidewalls of the tires, putting your tires at an increased risk of having a blow out — something no one wants to experience.

Tire blowouts kill about 500 drivers a year, and cause well over 2,000 accidents in the United States alone.

Even worse, most tire blowouts are caused by negligent inflation of your tires. Tire pressure management systems have been mandatory since 2007, so if you’re driving a newer car, your car will tell you when it’s time to inflate.

However, if you’re driving an older car, it’s extremely important to check your tire pressure at least once a month.

It is important to know that tire pressure can be lost without a tire appearing under inflated or flat. So just because a tire looks ok, doesn’t always mean it is.

What is the lowest tire pressure you can have and still drive?

We’ve already established why it doesn’t make sense to drive with low-tire pressure. However, if you’re wondering how “low you can go” and still drive your care, listen up.

If you have standard passenger tires (ninety percent of vehicles do) the lowest tire pressure you can generally drive with is 20 pounds per square inch (PSI). Anything under 20 PSI is considered a flat tire, and puts you at risk for a potentially devastating blowout.

How low does tire pressure have to be for the low tire pressure light to come on?

In 2008, a federal law was put into place requiring automakers to provide tire-pressure monitoring systems (TPMS) as standard vehicle equipment. The low tire-pressure warning light will display when the tire’s air pressure is 25 percent below the automaker’s recommended PSI. A 25 percent reduction in tire pressure is considered severe. So take the low-tire pressure warning as the warning it is!

What causes tire pressure to become low?

Why are your tires low on air? Obviously, tire damage will cause tire pressure to become low but it is not the only reason for tire pressure to drop. Tires can lose pressure over time and can be affected by cold temperatures. 

According to Car and Driver, tires normally lose about a pound of pressure for every 10-degree drop in temperature.  It is important to check tire pressure as the seasons change to account for changes in temperature and the resultant decrease in tire pressure.

You also have to account for your tires progressively losing air. On average, your tire looses about 1 PSI per month. With most passenger tires being inflated to around 35 PSI, it doesn’t take that long for you to get into hot water.

Which makes it extra important to know when your tire pressure is low, which requires you to know the recommended pressure in the first place.

How do I know what the tire pressure should be?

As a driver, you should be familiar with auto manufacturer’s tire pressure recommendations. You can find this information in your vehicle’s owner’s manual. It can also be found on the drivers-side door jamb.

How do tire-pressure monitoring systems work?

Have you ever wondered how the whole low-tire pressure alert works? It’s pretty simple but interesting at the same time. 

Tire-pressure monitoring systems use a sensor which is located in the pressurized pocket between the wheel and the tire. The sensor constantly measures the air pressure within the tire and transmits that information to the vehicle’s onboard computer. If tire pressure is low, the driver will be alerted by a low tire-pressure warning in the instrument display. Just want you (don’t!) want to see!

Can low tire pressure be caused by cold weather?

Yes! Those miserably cold days can definitely cause tire pressure to decrease! Tires generally lose about a pound of pressure for every 10-degree drop in temperature. You should check tire pressure when the temperatures dip down, especially if you live in a colder climate.

Just another reason that I love living in Florida. 

How do you check tire pressure?

So the decision has been made to buck up and check your car’s tire pressure. Nice job.

It is a good idea to have a tire-pressure gauge in your vehicle. Although some gas station air pumps have gauges, they’re not always accurate or easy to reach. It’s much better to have your own tire gauge so that you can keep an eye on tire pressure at home or on the road. You can easily buy an inexpensive, hand-held tire pressure gauge at any auto parts store or major department stores, like Target or Walmart. 

Although these have been around for what feels like forever, newer digital gauges can be much more accurate. If you have it in your budget, spend the extra $5 and get a digital.

The best time to check tire pressure is first thing in the morning when the tires are “cold” or at least three hours after driving. Take off the valve cap and press the tire-pressure gauge firmly into the valve stem until the device produces a pounds-per-square-inch (PSI) reading. If you hear a hissing sound you’re releasing air from the tire and will need to push the gauge more firmly in the valve stem to get a reading.

Pressure readings are more likely to be higher (usually between 2 and 6 PSI higher) if the car has been recently driven and the tires are hot. If you do end up checking your tire pressure after driving, you should add a little extra air pressure to account for the artificially high tire pressure reading

How can I fix tire pressure?

If you find your tire pressure is low you will need to add air to the tire. Many gas stations have air pumps that you can use to top off your tires. Some machines take coins only but most will also accept a credit card for payment. It usually costs a dollar or two to use an air pump — this should give you more than enough time to add whatever air you need to your tires. 

To fix tire pressure:

  1. First, make sure you park your car near the gas station’s air pump. You should park close enough that the hose can easily reach all four of your tires
  2. Check your owner’s manual of the driver’s door jamb to find out the manufacturer’s suggested air pressure
  3. Remove valve stem covers
  4. Check tire pressure (see above)
  5. Press the end of the air pump firmly into the valve stem and depress the lever, if there is a lever. Some pumps allow you to set the PSI you want beforehand and will alert you when you have reached the selected air pressure; others will not. It is a good idea to check the tire pressure during the process with a tire gauge, if you have one. Inflate your tires to recommended PSI. 
  6. If you need to release excess air, press the center prong inside of the valve stem or you can use your tire pressure gauge to release excess air as well.
  7. Replace valve caps on each tire’s valve stem.

Bringing it Together

Tire pressure should be checked monthly.  Yes, it is another item on your to-do list but the few minutes it takes to check your pressure will extend the life of your tires, increase your gas mileage, improve your vehicle’s performance, and protect your safety and the safety of other drivers!

It’s worth doing.

You know what else is worth doing?

Getting 24/7 roadside assistance in case you ever suffer a blowout on the side of the road so you’ll never have to worry about being stranded. One call is all it takes.

You can get a tow, or a new tire and be back on the road as good as new with no hassle on your part.

This is one of the many perks you’ll get with an extended warranty policy from Protect My Car that can potentially save you thousands on expensive repairs like engine or transmission failure.

Most of our plans start at less than $2 a day. To see how affordable it can be to protect your car and get 24/7 roadside assistance to protect your car from breakdowns, visit pmcquote.com to get a free, instant quote with no phone call needed.