Yes, as you mentioned, the Ford Explorer/Firestone issue was due to UNDERINFLATING.

http://en.wikipedia.org/wiki/Firesto...ny_controversy

This thread is discussing INCREASING the pressure from what the vehicle manufacture recommended.

 

Mr. Kite,

Now go back and more thoroughly read my dessertation on the negative safety aspects of INCREASING a FWD or F/AWD SUV's tire pressure beyond what the manufacturer recommends. The Ford Explorer story was only used as reference.

 

I didn't see your second post. I clicked on the link in the email notification that I received for your first post and then responded. Regardless, I do not see how that changes anything.

I believe the Ford Explorer was prone to rollovers because of its short wheel base coupled with its high center of gravity. Ford's recommendation to lower the tire pressure did not change the key problems. Underinflated tires are more prone to blowouts. While underinflated, the sidewalls will flex more--causing excessive heating and wearing. This was a double whammy.

Here's a little something for you to read:
http://www.officer.com/article/artic...on=19&id=27281

Due you really think running tires at 44psi is putting us at risk?

 

Here's one take on overinflation.

BTW most law enforcement vehicles run 40 to 45 psi in their tires.
This would be viewed as overinflation by the mfg.


{Paul Brand, from the Minneapolis Star Tribune}

Q We hear a lot about low tire pressure these days and the risk it creates; yet I still see people driving with obviously low tires. It seems that we must be reminded about how dangerous it is to drive on underinflated tires. The government is even looking at low-tire-pressure warning systems for all cars.
I have heard people talking about overinflating their tires to increase fuel economy and extend tire life. I like the idea of better fuel economy, but I'm not trying to win a race or have my tires last forever.
Some of these drivers have oversize tires on trucks or SUVs with C, D or E load rating tires that can handle up to 80 psi, but that is way over the manufacturer's recommendation. What does overinflating a tire on street-driven vehicles do to handling and safety?
It depends on the definition of overinflation. The good news is that today's tires are engineering marvels -- incredible products of modern technology that deliver amazing traction in all conditions, a quiet comfortable ride, remarkable resistance to road hazards -- that last tens of thousands of miles. And here's the most incredible aspect of modern tires: They somehow survive our abuse. Underinflation, overloading, poor alignment, bad shocks, curbs, potholes, tremendous heat, subzero cold -- and still the tire rolls on and on and on.
The dangers of underinflation have been well-documented, and your letter serves as a timely reminder to check tire pressure regularly -- once a month at least. From the economics of shorter tire life and premature shoulder wear to the safety aspects of dull handling and unresponsive steering, underinflated tires do not serve the car owner well. Even brake performance is measurably affected by low tire pressure.
And to follow up on your comment about the government working toward requiring low tire pressure warning systems -- a number of car and tire manufacturers already offer these systems -- the government is also considering a mandatory six-year life cycle for tires. These measures reflect what I've been preaching for the two-plus decades I've been doing this column.
The most important and critical components on your automobile are the tires. The palm-size contact patches between the tire and the road must translate your efforts to accelerate, brake or turn into a force that will change the direction or speed of a 3,000-plus-pound motor vehicle. The tires must be in good condition, properly inflated with adequate tread to do this job safely and effectively.
You raise an interesting question about overinflation. Most "P-series" tires, which indicate passenger car application, operate quite well with pressures in the upper 20s to mid-30s. Readers of this column have read many times my recommendation of 32 to 35 pounds per square inch (psi) for most cold tires.
"LT-series" tires, which are for light trucks or SUVs, are typically be inflated to between 35 and 50 psi, with some heavy-duty applications calling for more than 80 psi.
So, what is overinflation? On "P-series" tires, we've experimented with cold pressures in the 40-to-45-psi range on law-enforcement Crown Vics and Caprices and haven't seen a huge downside in terms of handling or performance. At higher pressures, tire stability is improved, as is resistance to heat build up. The ride quality suffers a bit, with the stiffer sidewalls stiffening the ride noticeably. Will the tire wear faster overinflated? Perhaps, but only along the center ribs if at all.
We've even tried inflation pressures above 50 psi, and found that gross overinflation caused the tire to skip or chatter across the pavement during extreme cornering.
Our experiences during law-enforcement training confirmed that pressures in the 40-to-45-psi range worked quite well on these 4,500-plus pound squad cars.
With the light trucks and SUVs, we ran through these programs, we made sure tire pressures were at least 45 to 50 psi, even higher on 1-ton trucks. With the weight and heavier loads of these vehicles, higher inflation pressures meant tire stability and safe operating temperatures, as well as optimal handling for these big rigs.
So, as you can tell, we haven't found a safety issue with inflation pressures above the carmaker's recommendation. And that's confirmed by the tire inflation information found on every tire's sidewall. In a nutshell, this information indicates the pressure at which the tire will support its maximum load. For "P-series" tires, this is 35 psi, 44 psi or 51 psi for standard load tires.
Thus, to answer your specific question, I do not think passenger car tires are overinflated until pressures exceed 40 to 50 psi, depending on the tire and vehicle. I believe inflation pressures in the 32-to-35 psi range, which might be above the carmaker's recommendations for that vehicle, will improve braking and handling to some degree, provide a somewhat better margin of safety in terms of heat buildup, and will not significantly shorten tire life because of accelerated wear.
Send questions to Paul Brand, Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488 or paulbrand@startribune.com. Please explain the problem in as much detail as possible and include a daytime phone number in case I need more information. Because of the volume of mail, it isn't always possible to send a personal reply.

 

This one is from retread.org

Q.At what point will a truck tire burst from overinflation?
Most new or undamaged medium radial truck tires can withstand three to four times the recommended pressure before bursting. In fact, the rim usually fails before the tire. ITRA has conducted several burst strength tests on new and used medium radial truck tires with special reinforced rims. The tires were pressurized with water. Most recently, three new tires and 13 used tires were "burst tested" with the lowest pressure burst recorded at 300psi and highest at 540psi for an average of 420psi. All of the test tires failed in the bead area.

 

I believe that most Explorer roll overs resulted from an underinflated tire coming off the rim under stress. This catastrophic deflation caused the roll over.

MM

 

The truth is...I don't know.

But on the other hand why would anyone take the chance, assume I'm wrong..??

An easy test might be to see how quickly the vehicle stops with normal inflation vs over-inflated. You'd have to disable ABS and then put each configuration through a long enough drive cycle to get the tires up to normal operating temperature but the effort might very be worthwhile.

 

I think you need to define what you consider over-inflation and under-inflation. Otherwise, you are speaking totally arbitrarily.

 

No, I don't know about others but for my vehicles the manufacturer's recommended tire pressures are usually on the inside of the glove box door, on the door pillar, or in the owners manual.

Personally I would consider any intentional deviation from those recommendations as being either over or under inflated.

 

You are referring to the car manufacturer's recommended pressure. Do you think everything above this is over-inflation? I would say that anything over the max pressure stamped on the sidewall is over-inflation. You will be hard pressed to find any data that suggests that the max sidewall pressure is unsafe. I think I and others have provided a lot of nice information that suggests pressures up to the max sidewall are totally safe (and maybe even safer). Do you have anything that suggests otherwise? The following does not count and there really is no need to rip apart that statement.