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Tire Pressure - Dangerously Underinflated!

Today, I drove from NYC to Pittsburgh (a 370 mile, 6-hour drive). What I didn’t realize was that since my last tire air pressure check only a month ago, the pressure had dropped from 30 PSI to 22 PSI for the rear left tire and to only 13 PSI for the rear right tire! Unfortunately, I decided to do the check AFTER the trip - how silly of me.

Am I lucky to be alive? - having driven 370 miles, mostly at around 70 mph on a major, busy highway without having had one of the rear tires blown-up or something? I drive a 2005 Pontiac Grand Prix, if it matters.

Mucho Gracias!

Low tire pressure at high speeds builds heat in the tire. This can cause a tire to fail.


Yes, you are very lucky.
When you drive–especially at high speed and for long distances–with dangerously underinflated tires, the tires’ sidewalls flex to a very great extent, building up damaging heat in the cords that form the tire’s carcass. Most likely, the very cold winter temps helped to keep the tires from self-destructing, but that doesn’t mean that you haven’t done internal damage to those tires.

If the tires are more than a couple of years old, I would suggest that you err on the side of caution and replace them, simply because the likely internal damage could result in those tires self-destructing at any time.

And, for the future, please bear these factoids in mind:

Tires typically lose 1 lb of pressure for every 10 degree drop in temperature
Even with steady ambient temperatures, tires will inevitably lose some pressure over time
Tire pressure should be checked at least once a month, and should ALWAYS be checked just prior to a road trip

LOW pressure is what caused all the Firestone / Explorer blow out years ago.
Some bonehead ( don’t know if it was Ford or Firestone ) decided to ‘‘recomend’’ the too low pressure on all the Explorer door info tags and anyone who followed that instead of normal logic had tire problems.

So, yes you dodged a bullet and learned a valuable lesson too. ( Do your own ‘‘pre-flight’’ walk around more often )

Far too many drivers never even look as they hop in and drive off…let alone looking at the passenger side tires.

Agreed, and you really need to have the sidewalls of those tires inspected and quite likely will need to have them replaced.

A tire with low pressure can ruin the sidewall inside of 20 miles and they’re subject to blowout after that. In a word, lethal.

Agree with above, low tire pressure is a greater threat than high tire pressure. I do not know how to check for safety of the tire, but if you are treadware due for new go for it, otherwise carry a spare and 2 hands clutched tightly on the steering wheel. Luckily for you rear wheel blowouts are more forgiving than front wheel blow outs in my experience. Got a spare?

In an SUV or a minivan you could consider yourself lucky to be alive.
In a Grand Prix you’re just lucky you didn’t get a blowout, which might or might not have resulted in a serious accident.

Kudos for checking your tire pressure. And for recognizing that you should have done it sooner. I check mine regularly. Along with my fluids.

Considering how low that right rear tire was, how long the trip was, and how cheap and critical tires are, I’d think about swapping out the rears for new rubber. It’s cheap insurance.

Agree with the others. The 13 psi one was the most troublesome. That’s pretty low. Winter is a problem since with the temp drop, the pressure will drop, plus unless you have your compressor a lot of the service station air hoses are frozen up. One of the problems is that at low pressure, the tires can lose their seal and go flat on you. You should have experienced some handling problems though if you drove all that distance with the tires that low.

Yes, you did dodge a bullet. As a CDL driver, I have a habit of at least glancing at my tires before getting in my car, especially in the morning, first time I drive it during the day. I’m required to check my bus over before driving it every day. If I take a long trip in the car, I check tires, fluids, etc…before leaving.

Some of the regulars here seem to be against tire pressure monitoring systems, but I’ll observe that this wouldn’t have happened with today’s cars.

I’m a regular, and I’m not against tpms

I think it’s a great thing

Me either. Used it several times.

I wish they stuck with the tire monitoring system that only used the Antilock sensors in each wheel. It was simple and it worked.

I too have nothing against TPMS. I think it should be optional rather than mandatory, but I have nothing against it.

Years ago, I learned to keep an eye on tire pressure. I had snow tires mounted on separate rims and when I changed back to the summer tires on the rear (this was in the late 1960s and we had RWD vehicles), I noticed that the car didn’t handle well around town. It dawned on me that I hadn’t checked the pressure in the tires I had just put on. The tires were down to about 22 psi, I hadn’t driven very far–probably less than a mile, but it made me realize how important proper inflation is.
I am in favor of tire pressure monitors. However, I prefer the new style built into the valve stems. I had the monitor on my Sienna warn me of a low tire on the way home. When I got home, I inflated the tire and then did find a nail in the tire. The pressure held for the 2 miles I had drive to my tire dealer. I am not quite as fond of the tire pressure monitors that work off the antilock brakes. My wife, another colleague and I were returning from a conference in St. Paul, MN to our home in east central Indiana in a Ford Windstar from our institution’s fleet. We left St. Paul and noon and I was driving the late shift while everyone else slept. We were on a stretch of interstate 74 that was being repaired. Only one lane in our direction was open and that lane had been milled for resurfacing. The tire pressure monitor came on and there was nothing I could do–no shoulder to pull off. We continued until I got to an exit. I could not tell that any tire was low. Fortunately, the owner’s manual was in glove compartment and it gave the procedure to turn off the monitor light which we did. It didn’t come back on and I surmised that the vibration of the milled pavement set off the monitor light.

I wish they stuck with the tire monitoring system that only used the Antilock sensors in each wheel. It was simple and it worked.

Except that it didn’t. If it gets cold and all of the tires lose 10lbs of pressure, the TPMS will have no idea that anything is wrong because all of the wheels will be returning the same data. The better TPMS that actually measures direct tire pressure is more accurate and useful.

Some of the regulars here seem to be against tire pressure monitoring systems, but I'll observe that this wouldn't have happened with today's cars.

Funny you shoud say that…

had lunch with my dad, today, who drives a '06 Caravn w/ TPMS. Of course, the batteries have long since died, and he now has a “constant” alert. While I was walking out from lunch, I saw his RR tire was VERY low, and I told him to take it to the nearest gas station.

Point being, it can and does happen on TPMS-equipped cars. So long as there is no state mandate to keep the stuff operating, all the federal madates guarantee nothing.

I’d argue that the “KISS” version that runs off the ABS sensors would work better for owners of aged cars, as there are no batteries to disable the system in a half-dozen years.


Some of the regulars here seem to be against tire pressure monitoring systems, but I'll observe that this wouldn't have happened with today's cars.

Maybe, Maybe Not. Around here I see alot of cars driving around at night with Illuminated warning lights, You will still have people ignoring the warning lights.

I was behind a lady last week who was driving a trailblazer. The RR tire was flat. I actually pulled in after her in a parking lot to tell her and she had no clue it was flat. The tire was only a few days old and the sidewall had been ruined, not sure why it went flat, but she drove on it for quite a while judging by the sidewall.

There was snow on the roads, but geeze, you would think a flat tire would have been noticeable.

She had 2 kids in the car, and as usual you can’t make this stuff up.

The problem with any TPMS system is that it’s now just another warning light on the dash that people have been trained to ignore, like check engine, traction, ABS, etc. It seems to me that people either fix their cars or they don’t.

If we really want to make sure all tires are properly inflated why don’t we enact regulations requiring that tire pressure be checked and adjusted to spec any time a car is in any kind of auto service facility or fleet service center and that the pressures be documented on the repair order. You bring your car in for a headlamp and you get your tires aired up by the shop!