Quote, originally posted by 1oldbanjo »Stealth:Cars driven at speed need higher pressure to perform properly - daily drivers will perform better and get better tire mileage with normal pressures. Here is a link for the increase in pressures related to high speed driving. You don't need pressures over 38 psi until you get to speeds above 130 mph.
http://www.tirerack.com/tires/...id=72Excessive wear on the outside of the tire will occur with underinflated tires - or with spirited driving around freeway ramps. As I indicated earlier 36 - 38 pounds will generally correct that problem - however if you continually drive in an aggressive manner around corners you can count on wearing your tires edges out as they will be scrubbing around the corners. Here is a link for tire pressure during competition - notice that most pressure recommended are below 40 psi and that they state that tire pressures should be returned to the normal pressures when returning to the street. These pressures will provide the best traction and handling on dry pavement - pressures can be increased in wet weather to help avoid hydroplaning.
http://www.tirerack.com/tires/...id=58I know that you will experience excessive tread wear in the center of the tread by running higher than normal pressure from my experience, from the recommendations of the manufacturers, and from having worked at a tire dealer. Here are some links for overinflation:
http://www.tirerack.com/tires/...hid=1h ... rinflation reduces the tire contact surface and requies a smaller area of tread to endure the imposed loads during acceleration, cornering or stopping- and the forces on the smaller footprint exceed the available traction sooner than a tire that is properly inflated and has a larger footprint. If you don't believe that overinflation reduces your traction during severe stopping or acceleration find a vacant parking lot or road and drive 60 mph and stomp on the brakes to reach the limit of traction at 60 mph with 44 pounds of air in your tires and mark the place you come to a full stop - then repeat this test with 36 psi in your tires. Repeat this when accelerating away from a dead stop and see what happens - I bet you can leave a long skinny black mark with 44 psi in your tires and a shorter wider black mark with 36 psi.I really don't consider this to be an arguement - but I really don't believe it is good for the average driver to be putting more than 36 psi in their tires. Police officers who may need to drive in a high speed persuit may very well be in need of higher pressure than those of us who are driving 45 - 65 mph on our way to work (especially when it may be raining during the persuit and they need to avoid hydroplaning). I have a considerable amount of experience driving autocross and track events and I know that tire pressures near 36 psi will provide the best peformance - and tire pressures around 30-32 will give the best tread mileage during normal driving. I have worked at a tire dealer and I do the maintenance on our company vehicles and I have seen the effects of over and under inflation. The tires that are ignored and run underinflated wear the outside of the tread - and the people that read the maximum pressure rating on the sidewall of the tire and overinflate their tires wear out the center of the tread. This is especially common in pickup trucks where the maximum pressure rating for a loaded tire is used - and then the owner drives his truck around without any loads in the back.So....that is what I believe after having owning, racing and working on my cars for the last 36 years (I am 52). I was once very much into racing and speed....then I got married moved to the country and bought a farm.....I don't have a "need for speed" like I used to. This is a picture of the last performance car I built and raced and it was a 1970 Porsche 914/6. It had a 3.5 liter twin plug 6 cylinder motor from a Porsche 911 race car that ran in the Portland, Oregon area, 9" wide tires, slicks, and weighed about 2,100 pounds ..... it was about 340 HP and would do the quarter mile at 12.95 seconds and 113 mph - top speed was about 145 with the gearing it had and it would get their really fast......and it had about 30 psi in the tires! NICE...!!!!