Tire Pressure for 2011 A6?
02-23-2011, 11:50 AM
#21
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I wouldn't use the "max load" pressures given. If you look at the pictograms near the tire pressures, you'll see that those pressures are recommended for increased load in the rear of the car.
With tires, there is an "effective radius" to the wheel/tire caused by the flattening of the bottom of the tire under load. (i.e., the "effective radius" is the distance from the hub center to the ground when the wheel is under load).
Tire pressure changes can be viewed in terms of contact patch as well. If the tires are "flattened" to the same degree at front and rear, the contact patches will be the same size.
You really want the effective radius and the contact patches to be the same at all four corners. That is why most recommended pressures are higher in the front (where the weight is).
On an AWD car, this is even more important, because it will affect how torque gets put down to the pavement.
If the pressures are not properly adjusted for load, neither the contact patches nor the effective radii will be equal. The different radii result in different torque applied, and the different sized contact patches will affect the traction available at each corner.
I'm sure all the Audi electronics can compensate for this, but I had a Subaru (much simpler technology) that was very sensitive to this. One time I did my brakes, and while I had the car jacked up I decided to rotate the tires from front to rear on each side. I neglected, however, to adjust the tire pressures. I ended up,then, with a higher pressure in the rear (the lighter end of the car).
Next highway trip it rained, and with even moderate acceleration at highway speeds, the car fishtailed pretty alarmingly. Correcting the tire pressure differential front to rear solved the problem.
The "Max Load" recommended pressures are designed to compensate for rear seat passengers and a trunk full of their luggage. For regular daily driving
- say, front passengers only, no luggage - you should use the standard recommended pressures, which are generally 2-3 lbs higher in front than in rear.
Just my $.02.
With tires, there is an "effective radius" to the wheel/tire caused by the flattening of the bottom of the tire under load. (i.e., the "effective radius" is the distance from the hub center to the ground when the wheel is under load).
Tire pressure changes can be viewed in terms of contact patch as well. If the tires are "flattened" to the same degree at front and rear, the contact patches will be the same size.
You really want the effective radius and the contact patches to be the same at all four corners. That is why most recommended pressures are higher in the front (where the weight is).
On an AWD car, this is even more important, because it will affect how torque gets put down to the pavement.
If the pressures are not properly adjusted for load, neither the contact patches nor the effective radii will be equal. The different radii result in different torque applied, and the different sized contact patches will affect the traction available at each corner.
I'm sure all the Audi electronics can compensate for this, but I had a Subaru (much simpler technology) that was very sensitive to this. One time I did my brakes, and while I had the car jacked up I decided to rotate the tires from front to rear on each side. I neglected, however, to adjust the tire pressures. I ended up,then, with a higher pressure in the rear (the lighter end of the car).
Next highway trip it rained, and with even moderate acceleration at highway speeds, the car fishtailed pretty alarmingly. Correcting the tire pressure differential front to rear solved the problem.
The "Max Load" recommended pressures are designed to compensate for rear seat passengers and a trunk full of their luggage. For regular daily driving
- say, front passengers only, no luggage - you should use the standard recommended pressures, which are generally 2-3 lbs higher in front than in rear.
Just my $.02.
02-23-2011, 12:13 PM
#22
Thanks for the compliment. Maybe it'll help somebody out.
The point is, whether you read your manual or not, the heavier end of the car should have a higher tire pressure. Usually 3-4 lbs for most cars.
My 2005 A6 3.2 had recommended tire pressures (inside the tank lid) of
36 front, 33 rear for normal load.
My 2008 A6 4.2 doesn't have a sticker on the gas lid. There is a sticker on the driver's side door post that lists 39 front and 42 rear (what?!?). I don't know if that's an Audi sticker or not. It only lists those pressures without mentioning load factor.
When I checked the manual, it still lists 36F/33R as "normal" for the 3.2, but gives 39F/35R for the 4.2 V-8 (makes sense to me - heavier engine and all). For Full load conditions it gives the 39F/42R as previously mentioned, but 3 passengers and their luggage (their rock collections, presumably) adds a lot of weight to the rears.
This is why I wish to hell the A6 came with the individual tire pressure/temp monitoring that the A8 has. The parts are out there to retrofit it, but I figure it's about $850-1000 bucks for parts, not counting a lot of fiddly labor and dismounting and re-mounting/balancing the tires to replace the sensors.
The point is, whether you read your manual or not, the heavier end of the car should have a higher tire pressure. Usually 3-4 lbs for most cars.
My 2005 A6 3.2 had recommended tire pressures (inside the tank lid) of
36 front, 33 rear for normal load.
My 2008 A6 4.2 doesn't have a sticker on the gas lid. There is a sticker on the driver's side door post that lists 39 front and 42 rear (what?!?). I don't know if that's an Audi sticker or not. It only lists those pressures without mentioning load factor.
When I checked the manual, it still lists 36F/33R as "normal" for the 3.2, but gives 39F/35R for the 4.2 V-8 (makes sense to me - heavier engine and all). For Full load conditions it gives the 39F/42R as previously mentioned, but 3 passengers and their luggage (their rock collections, presumably) adds a lot of weight to the rears.
This is why I wish to hell the A6 came with the individual tire pressure/temp monitoring that the A8 has. The parts are out there to retrofit it, but I figure it's about $850-1000 bucks for parts, not counting a lot of fiddly labor and dismounting and re-mounting/balancing the tires to replace the sensors.
Last edited by TVR1977; 02-23-2011 at 12:17 PM.
02-23-2011, 01:08 PM
#23
AudiWorld Super User
When I checked the manual, it still lists 36F/33R as "normal" for the 3.2, but gives 39F/35R for the 4.2 V-8 (makes sense to me - heavier engine and all). For Full load conditions it gives the 39F/42R as previously mentioned, but 3 passengers and their luggage (their rock collections, presumably) adds a lot of weight to the rears.
02-23-2011, 05:09 PM
#24
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02-24-2011, 02:58 AM
#25
AudiWorld Member
Thread Starter
Just Want to Be Clear :)
I just want to be clear on why I posted this and thanks for all the input. All the information has been helpful.
A6 3.2 Continental ContiPro Contacts 245/40-18.
2005 A6 3.2 Normal Tire Pressure 33psi Rear 36psi front on the gas latch.
2011 A6 3.2 Normal Tire Pressure 42psi Rear 39psi front on the door frame.
Why did it change? Same basic chassis, same Continental ContiPro Contacts, with the same tire size. I had read that there was abnormal tire wear so the pressure was changed? I could be in left field, honestly. I saw one post for a 2011 3.2 A6 that listed the higher pressure. So I wanted to adjust my tire pressure for my 2005 A6 3.2 to the new listed pressures of the 2011 A6 3.2. If anyone else has a 2011 A6 3.2 with 245/40-18's I would be curious to what is listed in the door frame for normal load pressure.
Thanks again,
Rich
A6 3.2 Continental ContiPro Contacts 245/40-18.
2005 A6 3.2 Normal Tire Pressure 33psi Rear 36psi front on the gas latch.
2011 A6 3.2 Normal Tire Pressure 42psi Rear 39psi front on the door frame.
Why did it change? Same basic chassis, same Continental ContiPro Contacts, with the same tire size. I had read that there was abnormal tire wear so the pressure was changed? I could be in left field, honestly. I saw one post for a 2011 3.2 A6 that listed the higher pressure. So I wanted to adjust my tire pressure for my 2005 A6 3.2 to the new listed pressures of the 2011 A6 3.2. If anyone else has a 2011 A6 3.2 with 245/40-18's I would be curious to what is listed in the door frame for normal load pressure.
Thanks again,
Rich
02-24-2011, 03:03 AM
#26
AudiWorld Member
Thread Starter
Understood, that is exactly what mine lists. But what is it for a 2011 with the same tire size? I would hate to run down my new ContiProContacts if just adjusting the tire pressure to the 2011 spec. would save many miles.
02-24-2011, 04:18 AM
#27
AudiWorld Super User
Yeah, the US govn mandated some silly new rule a couple of years ago. We can thank the Ford Explorer drivers. The stickers do call out a MAX LOAD condition and nothing else.
Ask someone in Europe what their recommended pressures are. They are entirely different than what you'll see on the USA cars. I guess the laws of physics are different for American drivers
Ask someone in Europe what their recommended pressures are. They are entirely different than what you'll see on the USA cars. I guess the laws of physics are different for American drivers
02-24-2011, 04:21 AM
#28
AudiWorld Member
Thread Starter
Yeah, the US govn mandated some silly new rule a couple of years ago. We can thank the Ford Explorer drivers. The stickers do call out a MAX LOAD condition and nothing else.
Ask someone in Europe what their recommended pressures are. They are entirely different than what you'll see on the USA cars. I guess the laws of physics are different for American drivers
Ask someone in Europe what their recommended pressures are. They are entirely different than what you'll see on the USA cars. I guess the laws of physics are different for American drivers
02-24-2011, 04:27 AM
#29
AudiWorld Super User
I can reference a long write-up on the whole debacle should anyone have interest in reading it. I don't understand why so few are aware of what took place.
02-24-2011, 04:38 AM
#30
AudiWorld Member
Thread Starter
I would love to read that. I am totally unaware of the situation. So, are only max. loads listed for the 2011? If so, what is the proper pressure.