Correct tire pressure of 34 / 42 is ambiguous
#1
Racer
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Correct tire pressure according to the manual is
front 34
back 42
Is this when the tires are cold or hot?
My 18 year old E-class Benz gas flap indicates the pressure at both cold and hot. Our cars are sports cars that need precision, and why is that manufacturers fail to indicate it?
front 34
back 42
Is this when the tires are cold or hot?
My 18 year old E-class Benz gas flap indicates the pressure at both cold and hot. Our cars are sports cars that need precision, and why is that manufacturers fail to indicate it?
#2
Rennlist Member
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Correct tire pressure according to the manual is
front 34
back 42
Is this when the tires are cold or hot?
My 18 year old E-class Benz gas flap indicates the pressure at both cold and hot. Our cars are sports cars that need precision, and why is that manufacturers fail to indicate it?
front 34
back 42
Is this when the tires are cold or hot?
My 18 year old E-class Benz gas flap indicates the pressure at both cold and hot. Our cars are sports cars that need precision, and why is that manufacturers fail to indicate it?
#3
Nordschleife Master
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Tire pressures are ALWAYS set cold.
34/42 seems high. Isn't it 33/39PSI w/ light load?
34/42 seems high. Isn't it 33/39PSI w/ light load?
#4
Race Director
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2005-08 Carrera S COLD tire pressure is 33 front 39 rear. This is for 2 passengers and 1 suitcase. Cold tire pressure is based at 68 degree F. This is all in the owners manual.
#5
Poseur
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Cars routinely cite a tatget pressure and it is ALWAYS cold. (Citing a pressure WARM or HOT is WAY too imprecise because pressure is a FUNCTION of temperature). Standard day temperature is always 68ºF or 20ºC. Standard lapse rate for altitude is 2ºC per thousand feet (per ICAO and FAA).
#7
Nordschleife Master
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Cars routinely cite a tatget pressure and it is ALWAYS cold. (Citing a pressure WARM or HOT is WAY too imprecise because pressure is a FUNCTION of temperature). Standard day temperature is always 68ºF or 20ºC. Standard lapse rate for altitude is 2ºC per thousand feet (per ICAO and FAA).
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#8
Three Wheelin'
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nathan, i'm with you. pervert equals nert. of course, i'll just post something for edgy if i have a doubt. i'm a recovering engineer. doing that equation would constitute a relapse.
then again i can always ask mike to read the manual for me
then again i can always ask mike to read the manual for me
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#10
Nordschleife Master
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"Note that T is deg Kelvin - T=(278 + t) where t is in Centigrade. "
I sorry to correct you but the proper conversion from Celcius to Kelvin is C+273.15=K
I also set the pressures for my '09 @ 37 Front, 44 Rear with the 19" wheel option.
I sorry to correct you but the proper conversion from Celcius to Kelvin is C+273.15=K
I also set the pressures for my '09 @ 37 Front, 44 Rear with the 19" wheel option.
Last edited by 19_hole; 03-31-2009 at 08:08 AM.
#14
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I just went out and double checked the placard in the door of my '09 C2S and it states cold tire pressure is 37 front and 44 rear. Just drove over 850 miles in one day in the car and watched the pressure with outside temps at or around 55-65 degrees the pressure increased by 2-3 lbs per corner. I have straight air in the tire although I want to change to nitregen (sp)