Mt. Hamilton drive - PICS on the first page :)
#182
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[/quote]
God mode LOL!!!
#183
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#185
I really hope that isn't a true statement... How do people read "MAX PRESS. 50 psi" and think that is what the tire manufacturer recommends? Your tire doesn't have a recommended pressure, your car does.
#186
Originally Posted by danvuquoc' timestamp='1345651201' post='21955982
I just run my tires at the psi marked on the outside of the tires. 50 something.
#187
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Originally Posted by andrewhake' timestamp='1345653890' post='21956139
[quote name='danvuquoc' timestamp='1345651201' post='21955982']
I just run my tires at the psi marked on the outside of the tires. 50 something.
I just run my tires at the psi marked on the outside of the tires. 50 something.
[/quote]
I always thought the door jam was optimized (but for the OEM tires the car came with) and maybe a bit of adjustment was needed for individual tires. I normally run 35, and sometimes play with that up/down a bit when I change to a new brand of tires. I'd say its worth experimenting.
#188
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From tire rack:
Maximum Inflation Pressure
A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold." Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.
For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.
A tire's "maximum inflation pressure" may be different that the assigned tire pressure used to rate the tire's "maximum load." For example, while a P-metric sized standard load tire's maximum load is rated at 35 psi, many P-metric sized standard load performance and touring tires are designed to contain up to 44 psi (and are branded on their sidewalls accordingly). This additional range of inflation pressure (in this case, between 36 and 44 psi) has been provided to accommodate any unique handling, high speed and/or rolling resistance requirements determined by the tire and vehicle manufacturers. These unique tire pressures will be identified on the vehicle placard in the vehicle's owner's manual.
The tire's maximum inflation pressure is indicated in relatively small-sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum inflation pressure is branded on the tire in kilopascals (kPa) and pounds per square inch (psi). These values can also be found in the industry's tire load & inflation charts.
A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold." Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.
For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.
A tire's "maximum inflation pressure" may be different that the assigned tire pressure used to rate the tire's "maximum load." For example, while a P-metric sized standard load tire's maximum load is rated at 35 psi, many P-metric sized standard load performance and touring tires are designed to contain up to 44 psi (and are branded on their sidewalls accordingly). This additional range of inflation pressure (in this case, between 36 and 44 psi) has been provided to accommodate any unique handling, high speed and/or rolling resistance requirements determined by the tire and vehicle manufacturers. These unique tire pressures will be identified on the vehicle placard in the vehicle's owner's manual.
The tire's maximum inflation pressure is indicated in relatively small-sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum inflation pressure is branded on the tire in kilopascals (kPa) and pounds per square inch (psi). These values can also be found in the industry's tire load & inflation charts.
Disadvantages of Overinflation
An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.
An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.
#189
It is my opinion that under inflation is much worse for your tires than over inflation though. It is amazing how much more fun you can make a car with changes in tire pressure. Pretty much all my rentals I have been beating up on over the last year I will do a shakedown with the recommended tire pressures for the car. Then usually end up increasing the rear tire pressure about 5-6 psi since they have always been FF or AWD cars. You can make an understeering car much closer to neutral with the proper pressures. It is all pretty easy to understand, more pressure in the fronts and you will increase steering response but also increase understeer and decrease front traction. More pressure in the rears and you can increase turn in feel but also increase oversteer and decrease rear traction.
There is a pretty decent article about this here (random Google search):
http://www.team-integra.net/forum/bl...-handling.html
The recommended pressure in the door jam is for the OEM sized wheels and tires, but really it is going to stay pretty consistent with that across the board for most aftermarket wheel tire setups. As Casey mentioned, it really is just a matter of experimenting though. 35 psi tends to be the standard starting point. Higher pressure will definitely make the steering feel more responsive but what you gain in steering feel you compromise in the tire's overall contact patch. I have played with the pressure in rentals A LOT in the mountains. There is a sweet spot for every car, tire setup, and weather/road condition. All of those things should always be taken into consideration I think.
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