Tire pressure effects.

[boydsdodge]

I was just reading about some tire pressures and the writer sugested that you should run a pound for every hundred your car weighs.
Do you guys have any knowlege on tire pressures and what there effects are on handling and road feel, like vibrations etc. etc...?

[moparmaniac59]

I never heard that. I know a lot of factors effect wear and ride. I am a simpleton & always keep my tires between 30 and 35 psi. Never had any problems .....other than a wheel coming off!! I think that formula could be a bit excessive. Most tire manufactures don't recommend pressures in excess of 40 psi (I am talking your standard driving tire, not racing types), yet with that formula, an old school Cadillac weighing in at just over 4,000 lbs would have the tire pressure just over 40 psi.



                                                              Matt B.

[HP2]

That's not an unreasonable formula for a street car. Competition cars will vary from this considerably and pressures there are best determined using a temperature gauge.

The more pressure you put in a tire the lower its rolling resistance, the less contact patch it has, the more sidewall stability it creates, the more center tread wear you create, the rougher the ride.

Lower pressure does the opposite of above, plus increases operating temperatures which can lead to premature tread/carcass failure.

[Grancoupe]

I would seriously recommend you check with the tire manufacturer of what's on the car.

[Supercuda]

Proper tire inflation is different for every situation. For street use, and in some moderate performance applications, thebest determination of proper pressure is in the treadwear, and in the contact patch. A proper tread contact patch will be the width of the tread, with no shoulders touching, and with a result of even wear across the tire. "Chalking" the tire tread, and seeing where it rubs off, will help give an indication what this pressure should be. When you get into serious performance applications, it gets a little more complex, and the quickest and surest way of determining the correct pressure, is through temperature readings across the tire tread. When the correct pressure has been determined, a compromise is then made, between this optimal pressure and the pressure that gives the most desirable ride characteristics. These can be noise, road feel, harshness of ride, or fuel economy. My personal choice has always been for the best tire wear, which means that the tire is loaded evenly, and not too hard (riding more on the center of the tread), or too soft (riding more on the outsides of the tread).

[Aussie Challenger]

  Rule of thumb for most street cars is between 28 & 32, if constant highway use then maybe 34. Less than 26 and the the sidewalls of the tyre flex too much giving a loose feel. I empathise normal street use, light trucks and above 36 to 42.