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Underinflated Tires

I have a friend who insists driving on Underinflated tires is no big deal…and certaintly NOT a safety issue.

I disagree!

Any comments specifically spelling out the dangers would be appreciated.



I’ll spell it - he (she?) is an i-d-i-o-t!

Underinflation makes the sidewalls flex constantly, resulting in overheating, damage, and, finally, failure through a blowout. Blowout=bad, it can lead to sudden massive loss of control.

Not a danger, but your friend is also wasting some gas.

More information required.

If the wheel and tire size is the same as OEM, and the load cap is the same or near the same, then yes, under inflated tires are a bad idea.

On the other hand, if it has plus size wheels and tires, and the tires have more load capacity than the OEM ones, then being a little under inflated is no big deal (and will help the ride be less harsh).

under-inflated BY HOW MUCH??? A little will just cause sloppy handling and premature wear. A lot will lead to overheating and tire failure as texases said…

Here’s a link to a Tire Rack tech article that explains better than I can.

I assume the underinflation is from the correct pressure on the door frame sticker, not the Max Pressure value stamped on the side of the tire.

Ed B.

I totally agree with Caddyman and texases; your friend is an i-d-i-o-t and apparently has a death wish.

On top of the blowout danger involved, your friend is also ruining tires and affecting the handling of the vehicle.
And it’s entirely possible that during a sharp high speed emergency turning maneuver that an underinflated tire can peel completely loose from the wheel rim.
Hello, rollover.

Consider taking out a life insurance policy on them while naming yourself as sole beneficiary; just in case.


Let’s call it as it is. In addition to being extremely ignorant, your friend is likely also extremely lazy.

People tend to come up with all kinds of rationalizations to justify their laziness, and I think that this is what you are observing with your friend. Your friend is wasting gasoline, is buying tires more often than necessary, and is putting herself and others in danger through her practice of driving on underinflated tires.

My guess is that if you offered to take care of the periodic tire inflation chores for her, your friend would not object, unless she is also one of those extremely stubborn people who are NEVER wrong. If you plan on traveling in her car, then I urge you to take charge of this chore.

I agree with edb. Is that under the MAX inflation value on the tyre or under the RECOMMENDED inflation on the car?

An under inflated tyre is less safe. In addition to possible blowout it will not provide safe road handling, especially under emergency handling conditions.

Please reference the Ford-Firestone Explorers mess.

About the only situation where I will purposely underinflate the tires is when I’m driving off road through deep sand, like on a beach. Tires with only about 15 psi in them will float on top of the sand instead of sinking down to the axle and getting stuck. Just be sure to reinflate them before hitting the highway.
Nothing good comes from underinflated tires on the street.

Guy I worked with bought brand new tires for his car. Two weeks later his daughter borrowed it and went to a party…One of her “Friends” decided to play a joke on her and removed about 10lbs or air pressure from each tire. By the time she got home (about 20 miles) the tires were RUINED.

A few days ago my neighbors’ adult daughter came to visit her parents and they called me to take a look at her tires because I have a portable air tank. Her neighbor told her one of her tires looked low.

I checked the door label on her Ford Focus and it said 34psi front and back. I measured the “low” tire. It had 48psi. The other 3 tires ranged from 52-62 psi! And the tires were labeled 44psi max. She didn’t notice if the ride was a little harsh… I put them down to 36psi and sent her on her way.

Cheri, as you may have discovered when it comes to issue of safety this can be a rough crowd. But they’re simply trying to emphasize that this is truely a danger due to not only the possibility of catastrophic failure due to overheating but also due to serious impairmentof the car’s ability to handle properly and its loss of being able to make a proper evasive maneuver in an emergency.

Since you’re already in agreement with us and obviously concerned, perhaps you could show your friend this thread. It is the friend, after all, that needs convincing rather than yourself.

it’s a wonder they didn’t explode from so much pressure

Well, that depends on the type of tire - and a comparison to the original size and load capacity.

For example my car originally (in 1990) came with 185/55/15 tires. I currently run 1 plus size, with a wider tire - 205/45/16.

On a set of tires I had on in the winter (UHP all-seasons), with a load capacity much greater than required, running the OEM size “door” OEM recommended pressure makes it much too hard. Running them at 28 psi instead of the recommended 35 greatly increased ride comfort and in no way made for sloppy handling or uneven wear. And believe me, this being a sports car, the tires get pushed (although nothing like they do when the car is on the road course).

Now that is on a 2500 lb car, so as I said, more info is required to give a reasoned answer. Put the same tires on a 3500 lb car, and 35 PSI will probably be just right.

Changing the tyre size does mean the recommended pressure is no longer recommended. It means you are on your own. Keep in mind that few people have the access to a test facility that is necessary to determine what is proper pressure.

Ride comfort is important, but it does NOT equal safety. Your most comfortable ride may well result in an unsafe condition. (Read what happened to the Ford Explorer back some years ago.) That was a case of the manufacturer recommending pressure that gave the ride qualities that the target customer wanted, but they neglected to properly test those pressures for safety.