The great S4 tire air pressure controversy
10-23-2011, 09:57 AM
#21
AudiWorld Super User
Tire pressure should be set when the vehicle is still cold, not driven recently. The recommened normal load tire pressure for the 19" 35 series tires is different from the 18" 40 series tires. I use the recommended normal load pressures of 39 lbs front, 35lbs rear on 18" tires.
Why don't people look at the manual?
Why don't people look at the manual?
Last edited by m444; 10-23-2011 at 10:12 AM.
10-23-2011, 10:31 AM
#22
AudiWorld Super User
Per FMVSS 110, the pillar label shows only MAX LOAD: 5 passengers weighing 150lbs each plud 5 suit cases.
10-23-2011, 06:54 PM
#23
AudiWorld Member
The manual also says if there's a discrepancy between what's printed in the manual and what's on the driver's door sticker, the door sticker wins.
My previous S4 had both loaded and unloaded pressures on the door sticker. My B8 just has one pressure listed on the sticker.
So, 41 psi it is.
My previous S4 had both loaded and unloaded pressures on the door sticker. My B8 just has one pressure listed on the sticker.
So, 41 psi it is.
10-23-2011, 07:58 PM
#24
AudiWorld Super User
Well, it is Discount Tire. What are you going to do? 
But, back to tire pressure. With me a bachelor, I generally have a light load while driving - not that I'm a light-weight or anything like that...
Regardless, 39 PSI for my front tires seems agreeable to most everyone. But, how about those rear tires? Why would I want 35 or 36 PSI in the rears instead of 39? In other words, how does having less air pressure in the rear tires - compared to the front tires - change the S4's driving dynamics, handling, ride, gas mileage, etc.?
But, back to tire pressure. With me a bachelor, I generally have a light load while driving - not that I'm a light-weight or anything like that...
Regardless, 39 PSI for my front tires seems agreeable to most everyone. But, how about those rear tires? Why would I want 35 or 36 PSI in the rears instead of 39? In other words, how does having less air pressure in the rear tires - compared to the front tires - change the S4's driving dynamics, handling, ride, gas mileage, etc.?
10-24-2011, 04:11 AM
#25
AudiWorld Super User
ROW door stickers don't look like the stickers applied to cars bound for the USA.
10-24-2011, 04:29 AM
#26
AudiWorld Super User
It's an attempt to provide a more neutral handling experience during emergency manuevers by having equal contact patches at all 4 corners. It's been like this for years and it's what the ROW does.
ROW door stickers don't look like the stickers applied to cars bound for the USA.
ROW door stickers don't look like the stickers applied to cars bound for the USA.
10-24-2011, 06:31 AM
#27
AudiWorld Super User
JD, that's correct, it was the knee-jerk response of the US Congress in attempt to save Ford Explorer owners from themselves and resulting rollovers. Ohh, and don't forget the TPMS and its mandatory implementation in 2008 (for the USA).
I think some of the folks on this forum are very young and can't remember back just a few years. Cars in the USA have always had two inflation values: Normal Load and MAX Load. Are peoples' memory really that poor?
I can recall seeing a 3rd value that some Euro mfrs would add: recommended winter tire inflation pressures
10-24-2011, 06:43 AM
#28
AudiWorld Super User
Here's what the ROW sees on the door pillar:
Door jamb label from a Euro A5/S5 car =>
You'll note two scenarios (up to two people and 1 suit case and up to 5 people plus their luggage) They've provided little pictograms so you don't have to struggle with the Owner's Manual I believe the Canadians see a label like this.
I believe the Canadians see a label like this.
10-24-2011, 06:58 AM
#29
38 all around here, thinking of lowering the rears down to 35 after reading this thread.
However would that make the car more prone to under steer vs over steer, as some have stated, since the rear will now have a lower pressure leading to a larger contact patch which in return will be relatively reducing the grip ratio between front and rear?
However would that make the car more prone to under steer vs over steer, as some have stated, since the rear will now have a lower pressure leading to a larger contact patch which in return will be relatively reducing the grip ratio between front and rear?
10-24-2011, 07:34 AM
#30
AudiWorld Super User
Albert, the general objective is to keep four equal contact patches (for street driving). Audis and VWs are FWD cars, some with 4WD, obviously It's fairly common for FWD cars to have something like a 70 front/30 rear weight distribution. Maybe the Audi is a bit better than that, I don't know the precise values. It should be somewhat intuitive that one would need more air in the front tires (or less air in the rears), to equalize the contact patch for street driving, no? On most FWD cars, the front tires are doing almost all the work and the rears are just kinda along for "the ride", if I may.
It's fairly common for FWD cars to have something like a 70 front/30 rear weight distribution. Maybe the Audi is a bit better than that, I don't know the precise values. It should be somewhat intuitive that one would need more air in the front tires (or less air in the rears), to equalize the contact patch for street driving, no? On most FWD cars, the front tires are doing almost all the work and the rears are just kinda along for "the ride", if I may.