Tires?

[GasSavers_katman]

Originally Posted by Compaq888

I have read that numerous times. It was on a website for police officers. In the article it stated that the police cars only had the max side-wall pressure. They didn't go more psi for safety reasons. If higher pressure increases traction than why do people at the drag strips lower their tire pressure to gain traction???

With slicks you have to look at the scuff marks on the tire and adjust air to get total coverage. You also aren't going around corners. On the street, the higher pressure will keep that steel belted tread flat on the pavement.

[thisisntjared]

Originally Posted by Compaq888

If higher pressure increases traction than why do people at the drag strips lower their tire pressure to gain traction???

it depends on the traction you are talking about. higher pressure doesnt always increase traction. it all depends on the type of driving and type of tire.

wet driving - max pressure = max traction, the water is pressed out from the tires more efficiently instead of being cupped in the tire.

street driving - dealer recommended pressure is usually best for blending everything(comfort, fuel economy, stearing response, slip angles, etc) yea and as katman with the steal belts, i didnt think of that

drag racing - now keep in mind that everything is tuned for that launch. it depends on the car but any tire thats going to have power sent to it is around 13-20psi depending on the tire(slicks, drag radials, non racing tires) and the tires that will not have power sent to them are usually at the maximum. the two concerns with this are the contact patch and weight transfer. stiff tires have a very small contact patch and allow very little weight transfer. which is exactly what you want for the tires that wont need traction and will have weight either unnecisarily sent to or away from them. the tires that are receiving power are going to want the largest contact patch and be very flexible to weight transfering to or away from them. also as i will get into with auto-x driving lower pressures allow more flex in the tires sidewall and more flex in the sidewall allows a better launch. so when i drag race i put the front to 15-16 and the rear to 44

auto-x - the general rule of thumb for auto-xing and tires pressure is to do what feels right for your driving style in your car. people do all sorts of things. i will explain what i do and why i do it, but keep in mind that its for the way i drive in my front wheel drive car. i am not sure what is best for anyone elses cars. i put the front to 44(maximum) so i have the best steering response. in auto-x the launch usually doesnt mean as much as it does in drag racing, so i will sacrafice it in order to have a more connected feel with the car and what it is doing. the down side to this is that the front tires will give less warning as to when the are going to slide out. so again i do it this way because i know my car. i usually set the rears somewhere just shy of 25. this allows the sidewalls to flex much more. so while it feels pretty loose, in conjuction with the fat rear swaybar, it rear also follows the front through the turns very nicely since the slip angle is increased dramatically with such a low pressure. allowing me to take turns faster.

road racing tire pressures vary from car to car but usually are not as drastic in the difference as auto-xing. but truth be told, i know nothing about it.

i know this is a long post but in the end its almost impossible to explain this without going into suspension theory. i guess ask more questions if you have any.

EDIT: o yea i dont know anything about snow driving either

[GasSavers_katman]

What about ice racing? I can't imagine drilling all of those holes in those tires, then inserting and tightening all those bolts, and then grinding each bolt to a point!

[95metro]

Originally Posted by Compaq888

They didn't go more psi for safety reasons.

I thought it was because the insurance companies asked them not to, not specifically because it was unsafe. They still recommended going over for the savings and actually did it in their driving schools (if I remember correctly).