HX_Guy

I've had my A4 for ~2,000 miles now, bought it new, and yesterday the TPMS warning went off. Pulled over to check and none of the tires looked low so I drove the remaining 4 miles home.

Checked the air pressure on all 4 tires and it was at 52psi! Now the tidewater hot so that accounted for 2psi, meaning a cold tire pressure of 50psi.

According to the manual, under normal load, the front should be at 32psi and the rear at 29psi! Under a 4+ person load, it says 33/35 (which is what the sticker on the door says).

Now the super high pressure would explain why I found the ride to be stiffer than what I thought it would be but now setting the pressure at the recommended levels, the steering feels sluggish and takes a noticeable amount of more effort.

My gas mileage has also been much less than expected at around 22MPG 50/50 city/hwy. I know tire pressure affects gas mileage but I thought only if the tires are under inflated, right? If over inflated, that should actually help (smaller contact patch less friction) so can I expect the mileage to actually get worse with the correct tire pressure?

What are you guys running at with 18s? Anyone go above the recommended tire pressure? Any other thoughts?

grecomfs

Dealers routinely fail to normalize tire pressures from the elevated pressures used during transport from the factory (to prevent flat spotting of tires). This should happen during PDI but very often does not. Suggest running at or just slightly below factory recommended pressures.

HX_Guy

I actually deflated them to 1 psi above the factory recommendation and at the max load. Normal load says 32/29 and max load is 33/35 so I set mine to 34/36 as I do have 4 people in the car at least twice a week.

It sucks that I got so used to the high tire pressure that now the correct amount makes the steering feel very heavy, I really liked how light and easy it felt before.

uberwgn

HX, my car was the same when I picked it up two weeks ago...precisely 48psi (cold) in all four 18" tires*. I think I'm presently set to around 34/32.

My mileage and range has been somewhat deflating as well. I've never filled any car so often I'm hoping to pick up a few MPGs once the car gets some miles on it.


*makes me wonder what, if anything, is done at PDI

av_audi

You can probably push the fronts up by another psi or two. I have never trusted any dealer of any brand to get tire pressures right. After every service, that is the first thing I adjust. Once, my car was pulling heavily to the right after picking it up from the dealer. It turned out I had 30 psi all around, except for one of the fronts that was inflated to 40psi! The hood also popped on the freeway (thank god to the safety latch) because the mechanic hadn't properly closed it. Oh, and they had overfilled by a full quart, despite me giving them the right amount of synth oil

From now on, I am seriously considering bringing a tire gauge with me to any test drive, despite the certainty that the salesman will think I am a nut job. I think the wildly varying impressions people share about their test drives, especially for sports vs standard suspensions, is largely due to the completely out of spec tire pressures they might have experienced.

uberwgn

I did this when I test drove a Sport Pkg car back in Feb. Pressures were off but not too far.

Barrels41

My 2009 A4 18" Sport P7s are 33/35. That is what the sticker on the door frame says. I run winter tires also and use my own gauge at the tire shop before I leave. I have had 46 several times.

uberwgn

from Owner's Manual:

Cabal_san

Go by sticker on the B Pillar in US, even says it in that there manual excerpt.

Over-inflate a bit if you haul more ppl and get better mpg, IMO.

PS I think that NO dealers check PSI when you buy the car and head out of the lot. I have read this here & AZ countless times, and experienced this myself!

Note to any potential owners, check the tires befor eyou drive off the showroom!

uberwgn

Cabal, B pillar label shows MAX LOAD only. The chart in the Owner's Manual shows normal conditions.