Some Hypermiling techniques denounced by AAA

[Formula413]

Originally Posted by bestmapman

Surely you would agree that the tire manufacturer not the car manufacturer knows best about how the tire will hold up and what tire pressure is allowable.

Not necessarily. Car manufacturers spend a LOT of time testing every imaginable tire on any car they build until they find what they feel works best. Tire manufacturers are building tires to be used on a wide range of vehicles. How could a tire manufacturer put a recommended pressure on a tire without knowing what type of vehicle it is going to be used on? That's why they only list the maximum pressure, since they can be relatively sure that pressure above that would lead to failure on just about any vehicle.

[bestmapman]

Originally Posted by Formula413

Not necessarily. Car manufacturers spend a LOT of time testing every imaginable tire on any car they build until they find what they feel works best. Tire manufacturers are building tires to be used on a wide range of vehicles. How could a tire manufacturer put a recommended pressure on a tire without knowing what type of vehicle it is going to be used on? That's why they only list the maximum pressure, since they can be relatively sure that pressure above that would lead to failure on just about any vehicle.

So you have no references then.

[Blue07CivicEX]

Not that I necessarily agree with Formula 100% BUT here is a link supporting his argument
Tire Tech Information - Checking Tire Inflation Pressure

We can all agree tirerack is a reasonably reliable source for tire info?

Also, if I have to replace my tires 5k or 10k miles earlier (I have 80k mile tires) but I gain 2mpg over the life of the tires (we'll say 70k for calculating purposes).

Again for arguments sake we'll say I get 30mpg at the car manufacturer spec (35psi) puts me at $10666 in gas for the life of the tire at $4/gallon for the full 80k miles.

Now, assuming I get 32mpg with tires at 44psi but only get 70k miles out of the tires I would end up with $10000 even in gas for 80k miles at 32mpg BUT you have to factor in that I lost 10k miles worth of use on a set of tires, which comes out to 80k/$500 (price of 4 new tires mounted)*10k miles (number of miles wasted on the tire) this comes out to $10062.5 for 80k miles at high pressure.

Now, I understand these calculations are theoretical and actual results may vary but my point is, you have to do the math, if you have a 30k mile tire and over inflating it takes 10k off the life of the tire it's A LOT more significant then taking 10k off the life of an 80k mile hard compound tire. As always I welcome people to point out flaws in my logic, it's just the way I'm doing the math it seems like a 2mpg increase (which isn't unreasonable) would save $500 over the course of 80k miles.

K i'm done!

[dcb]

Originally Posted by Formula413

The maximum pressure is irrelevant to what pressure will produce the best mileage, the best handling, or the best traction. All of these will generally be far less than the maximum pressure, except fuel economy.

I'm sorry but I just read a study that had all these benefits at the maximum pressure, I will try and find it again.

In the meantime here is an article about real life police vehicles enjoying better performance, reduced hydroplaning and improved tire life by simply going with the max sidewall pressure (50).
Driving Under Pressure: Editorial & Features at Officer.com

[RH77]

From the Tire Rack regarding overinflation:

"...the size of its footprint in contact with the road is reduced."

We have learned the lesson time and again that the contact patch remains the same regardless of pressure. Same old rhetoric.

I don't trust a sales outlet, interested in selling more tires, to dictate false propagation of tire info.

Truly independent testing is required.

RH77

[Blue07CivicEX]

Give me about 2 years and i'll tell you how my 80k yoko's held up :-)

[Blue07CivicEX]

DCB is this the thread you were looking for

SAE-Paper

?? Has some good information, I personally don't know about the stopping since I haven't been stopping hard, don't need accelerating power, the ride is rougher but it makes you dodge the pot holes better other then that I haven't noticed much difference between 35psi and 44psi *shrug* wet weather handling seems about the same but again I don't beat on the car like I used to.

[dcb]

That's the one, thanks

[NoCO2]

Ok, so correct me if I'm wrong, and I very well may be because I am no expert on tires, however. I was under the impression that the mfg. suggested tire pressure was there mainly because tires heat up and the mfg. wants to make sure that when they heat up on the highway that there is enough headroom on the tolerance of the tire to hold the pressure based on the vehicle weight...is that correct? If so, then is it not also safe to assume that if you did some experimentation on your own to find out just how much the tires heat up under 'your' driving style and made sure by closely monitoring them that it didn't exceed sidewall tolerances that it would still in effect be safe to "over-inflate" your tires so long as the temperature when hot didn't surpass the limit?

[bestmapman]

Originally Posted by Blue07CivicEX

Not that I necessarily agree with Formula 100% BUT here is a link supporting his argument
Tire Tech Information - Checking Tire Inflation Pressure

We can all agree tirerack is a reasonably reliable source for tire info?

Also, if I have to replace my tires 5k or 10k miles earlier (I have 80k mile tires) but I gain 2mpg over the life of the tires (we'll say 70k for calculating purposes).

Again for arguments sake we'll say I get 30mpg at the car manufacturer spec (35psi) puts me at $10666 in gas for the life of the tire at $4/gallon for the full 80k miles.

Now, assuming I get 32mpg with tires at 44psi but only get 70k miles out of the tires I would end up with $10000 even in gas for 80k miles at 32mpg BUT you have to factor in that I lost 10k miles worth of use on a set of tires, which comes out to 80k/$500 (price of 4 new tires mounted)*10k miles (number of miles wasted on the tire) this comes out to $10062.5 for 80k miles at high pressure.

Now, I understand these calculations are theoretical and actual results may vary but my point is, you have to do the math, if you have a 30k mile tire and over inflating it takes 10k off the life of the tire it's A LOT more significant then taking 10k off the life of an 80k mile hard compound tire. As always I welcome people to point out flaws in my logic, it's just the way I'm doing the math it seems like a 2mpg increase (which isn't unreasonable) would save $500 over the course of 80k miles.

K i'm done!

The flaw in this argument is that tires last longer when inflated to max sidewall then when inflated 10 PSI less.