[niky]

Originally Posted by California98Civic

another is about HIGH speed driving and psi--not wear--

Not to mention the fact that it points out that higher pressure is necessary at higher speeds.

Originally Posted by ACEV

vibration was a predominant problem with overinflation.

Originally Posted by ACEV

The whole car wears a great deal more with overinflation rather than sticking with factory specs. The high cost of that damage to the car must certainly out-weigh any supposed savings in fuel.

Have you ever dealt with vibration damage? I have. What it equates to is changing your suspension bushings maybe a few hundred kilometers earlier (like 120,000 kms instead of 125,000) and tightening your body bolts.

One should note that modern cars are built for stiffer tires (as reflected in the higher door sticker pressures indicated versus older cars), and suspension design nowadays takes into account stiffer tire carcasses and higher inflation pressures.

Originally Posted by ACEV

He also said that he has seen very little difference in fuel economy when overinflating. While some may overinflate by 2 or 3 or 4 pounds for heavier loads, wet pavement issues and impact damages become significant.

Wet issues... so-so. Actually... it's dry performance that suffers, particularly in terms of braking. Hydroplaning lessens at higher pressure.

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There is no doubt that running very high pressures is bad for the suspension and if you run them high enough, the tire will experience greater wear. But there is no universal "too high" pressure. Some tires run fine over maximum sidewall. Some run crappy and experience center tread wear even below maximum sidewalll, even if you run them at the "proper" door pressures.

All tire carcasses will happily accept higher than maximum sidewall... though again, as some of us have pointed out, the diminishing returns beyond a certain inflation pressure (again, there is no universal pressure at which this happens) mean that you have to experiment to find the best compromise.