Common signs of low tire pressure
- TPMS warning light. The dashboard symbol, often an exclamation point inside a horseshoe shape, is the most direct signal.
- Heavy or sluggish steering. The car may feel less responsive when turning.
- Pulling to one side. A low tire on one side can make the car drift.
- Slapping or flapping noises. Sometimes heard from a very low tire.
- Longer stopping distances or less grip. Underinflated tires may not handle as well.
- Worse fuel economy. Rolling resistance increases (see tire size and gas mileage).
- Visible flattening or bulging. The bottom of the tire may look squashed. Looks can mislead, so confirm with a gauge.
- Uneven or fast wear. The outer edges of the tread may wear faster.
The TPMS light
Many cars warn you when pressure falls well below the recommended level, commonly around 25 percent under, though the exact threshold varies by vehicle. It is a late warning, so a tire can be low without the light being on. If it comes on, check each tire with a gauge. A light that flashes and then stays on can indicate a system fault; your owner’s manual explains your car’s behavior.
How low is too low?
Compare the reading with the number on your door jamb placard. Being a few psi under is common and usually corrected with a quick top-up, but the further below the recommendation you are, the more the tire flexes and the greater the risk of damage and handling problems. There is no single number that applies to every car.
Is 29 or 31 psi too low?
It depends on your car. If the placard says 32 or 35 psi, then 29 or 31 psi is below the recommendation and worth correcting. If your placard calls for a lower number, those readings could be fine. Always compare with your own placard. See the tire pressure guide.
Is it safe to drive on 17 psi?
For most passenger cars, 17 psi is far below the recommended pressure, and driving on it is not advised beyond a very short, slow trip to reach air. Severely underinflated tires can overheat and be damaged, sometimes without visible signs. If you have no way to inflate, consider roadside assistance. If the tire is damaged or will not hold air, use the spare or have the car towed.
What low pressure does to the tire and car
Low pressure makes the sidewalls flex more, which builds heat and speeds up wear. It can also reduce handling and braking performance and raises fuel use. Over time it can contribute to tire failure.
What to do
- Check all four tires with a gauge.
- Inflate to the placard pressure. Our guide to inflating your tires shows how.
- Recheck in a day or two. If a tire keeps losing air, have it inspected for a puncture or valve problem.
Temperature swings can also lower pressure; see how weather affects tire pressure.
When to see a shop
Visit a tire shop if a tire will not hold pressure, shows damage or bulges, or the TPMS light stays on after correct inflation. If the car vibrates or pulls despite proper pressure, read about wheel balancing vs. alignment.