Funny thing on this tread: all the concern is over blowouts. I would think the bigger concern of higher pressure is the reduced tire contact with the road. Obviously, that's the goal of inflating tires to such a high degree: less road contact means less resistance, which results to better gas milage. I would love to see actual studies relating stopping/cornering/control of a car equipped with 'recommended' pressure vs. higher pressure tires. I'm not asking for "it feels fine to me." I'm asking for "X% over pressure results in Y% longer braking distance."

 

Funny thing on this tread: all the concern is over blowouts.

I agree with your assessment. The reason I have commented on this in the past is because many inexperienced (young?) drivers read these comments about 40+ psig pressures on their TCH and think it's the next good thing to do as another high FE tip. I don't have a problem with something up to say 40 psig, but one should consider their driving conditions and realize you won't have the same handling and stopping abilities.

Some of the TCH'ers are in flat, dry level country. I live in the hills where it rains and there are sharp curves. There is no way I want to drive around on a set of stiff tires in my conditions.

If I only commuted in Arizona and never went over 60, then 45 may be OK.

 

The following advice is according to Barry Smith, who recommends running your tires at 3-5 PSI above the vehicle manufacturer's specification (taking into account increased ride harshness for normal drivers):

About Barry Smith:

 

The following advice is according to Barry Smith, who recommends running your tires at 3-5 PSI above the vehicle manufacturer's specification

I absolutely agree with this. Let's see; 3 to 5 psig would be 35 to 37 psig (I run at 36 psig_ I drive a lot of 70 mph on concrete roads, long distances). Even Toyota recommends 35 for high temperature driving (high speeds, high friction roads like grooved concrete or Arizona asphalt).

I'm still looking for the "expert" to say that driving on a set of tires with a manufacturers design of 32 psig is safe at 45+ psig or even 40 psig. I'm not interested in the number of people still alive that can say they run at that pressure all the time.

BTY, the 32 psig is not there for the strength of the tire (most are good for above 50), but it's there to give the "correct" area of contact necessary to safely drive the specific car based on the total weight and the weight distribution of that specific car.

It's absolutely pouring outside now. Yes pumped "tight" tires will cut through that rain on the road pushing it out of the way, up to the point that the very small contact patch starts floating. Then I have very little contact patch left to try and grab that asphalt. The only thing that might save me if I'm going slow enough is the VSC may be able to straighten me out as the car slows. But even it won't work until I get a grip. Just hope I slow down enough to "grab" traction before I slide across the median in front of some semi.

 

Thanks, Steve, for the Barry Smith quote. The question I have for him is why do manufacturer's recommend a "low" tire pressure if all that he says is true. My assumption (and yes, I know what "assume" means) was that the tire and car manufacturers collaborate on the issue to determine the best tire and tire pressure for a particular car model. Could it be that 32 psi is a cold "starting" pressure and that with road use and heat the tire will eventually end up at 35-37psi anyway? If the tire is already inflated to 35-37 psi then the road usage would put the effective pressure at 38-40 psi.

 

...more inflation pressure improves the fuel economy, wet traction, snow traction, tire durability, tire wear, steering response, but increases ride harshness.

I'm having a hard time leaving some of these comments alone. I have this fear of someone like my daughter who perhaps is just graduating from college and are purchasing their first car reading this stuff and saying "what a great idea" without considering or knowing the consequences.

What I really wonder about is what Bill Smith has to say about 10 to 15 psig over design. That seems to be the point of our disagreements.

To say "more traction" is very misleading.

More traction can mean many things. For trucks off road, less air is better traction, for dragsters less air means better grip. I don't know what Nascar runs (as they go high speed and around curves) or even Formula 1 drivers (curves both two directions)
but I agree up to a point more air will make the tire bite into snow and water better (note that dry traction is not one of the items mentioned).


If someone really drove 20 mph in the rain, more air probably would be safe, as the speed increases the harder tires would cut through the water rather than "flatten" out and float. But once the tire floats (and they all eventually will if you're driving normal speeds in the rain), you have less contact patch trying to grab back that grip with highter pressure tires.

I believe tires designed for rain ran at higher pressures would be a better option for those of you in the normally dryer, hot regions. At least then at 50 psig you would have a tire that could over compensate for less compact patch with an improved tread design to chanel water away when it started to rain.

 

Gents,

I'm pleased that people are doing research and all about this subject. Knowledge is good.

But there is another kind of knowledge too - it's called "personal experience." How many of us have had blowouts? Many of us have had at least one blowout. And you know the VAST majority of blowouts are caused by UNDERINFLATION, right? Google the subject. My last blowout was because of underinflation.

Tires today are a LOT better than they were 20 years ago. Other than the Ford Exploder issue of a few years ago, tires have come a long way.

OK, with the risk of blowouts MORE LIKELY with underinflation (fact) then the logical conclusion is that overinflation would lead to FEWER blowouts. That's point one.

Point two is that since tires are better now, we as owners of tires can "worry less" about tire problems.

Point three is that we know that overinflation leads to higher MPG, because of less rubber on the road and thus less rolling resistance.

Here's where personal knowledge comes into play: I've got 30,000 miles on two different hybrids using "overinflation" and I have so far ZERO negative issues - no odd wear, no loss of traction, no blowouts, no problems.

Wayne Gerdes, considered the World's Greatest Hypermiler (or if not, at least he is in the top three) has logged many many thousands of miles on his cars using overinflation and has reported no negative issues. He's actually the person who convinced me that overinflation is OK.

My situation is different that some of you, as I have stated. About 95% of my miles are on DRY city streets, at speeds under 45 mph. I don't need to worry about lost traction. I really have convinced myself that blowout is not a danger. From the miles I logged thus far, I have seen no uneven wear or tire damage.

So each person should make their own decision on tire inflation. My contention and my personal experience tells me that it is a good idea for me. YMMV....
.
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I've dialed up the voltage in my house from the recommended 120v to 132v. This modest gain of 10% makes my lights brighter, my stereo louder, and my computer faster. Known as the father of the 'Hypervolters' I have found the inconvenience of replacing light bulbs every week and the smell of melting plastic to be of little consequence compared to the benefits of more light, more sound, and more computer cycles.

 

Danger... Danger, Will Robinson! High voltage can lead to dangerous levels of comedic overtones.

 

lars-ss:

Your logic on point one is faulty. The logical conclusion is that PROPER inflation would lead to FEWER blowouts. You can't conclude anything about overinflation with the information you've given.

Like you, I've got lots of personal knowledge. However, I don't believe that one should generalize too much based on it. For instance, in my youth, I never had any accidents drinking and driving. Should I conclude that it is safe to do so? I would really like a little more evidence than your personal experience before I decide that to take the risk of overinflating my tires.