streetrod

I have 255/35 R19 tires on my A4. On the chart inside the door B pillar it says Front 38, Rear 42. But in the owners manual it says Normal load conditions Front 32, Rear 30 and for Full load conditions Front 35 Rear 35. I wonder why the big discrepancy between the chart on the car label and the owners manual. Also on the chart in the car why would the front pressure be lower than the rear? Has anyone else noticed this? Also what pressure are you guys running?

Macallan21

Staggered pressure is based on the loads on those sides of the car. Follow the pillar, not the owners manual.

jadatis

pressure advice is all about actual load on the seperate tires.
A bit about speed and alignment in the way of camber angle ( tires like this on the ( virtual) axle /-\).

So the advices in the manual are based on a higher weight on the front axle then rear, wich leads to lower pressure on the back.
An advice that was usual in Europe before 2000, but after that for normal advice the GAWR's where filled in for normal advice.

This is the reason for lower at back, but for other reasons the pressures need to be higher.
After 2000 they discovered that the maximum load of the low higt/width division tires you have ( the 35) was given to high on the sidewall. I have calculated from graphics I got hold of in wich 27% deflection of the free flexible part of sidewall of a 35% H/W tire where a 80% H/W is save a 20% , that you have to substract 20% of the given maximum load of sidewall.

To make a long story short, the tire-makers are overreacting to the Ford/Firestone Affaire. So You can use probably lower then the advices on the door-pillar, but higher then in the books.

If you give more details of car and tires , I can calculate it for you.

uberwgn

It's Federal law for the USA: B pillar sticker shows MAX LOAD conditions only.

Refer to your Owner's Manual for normal loads vs. MAX Load.

streetrod

Thanks everyone for the replies and great info. For what its worth I called the Audi dealer today and asked them. They said to follow the sticker on the B pillar but the technician told me his personal advice was to run 35 - 35.

Barrels41

If the car rides hard lower the rear tire pressure a bit. Especially if you mostly drive alone with an empty trunk. Tire pressure varies with outside temperature and driving speed. I find I get different readings with different tire gauges also. I run a bit lower than the door pressure but higher than the owner's manual.

streetrod

thx uberwgn, I agree it makes sense the sticker shows max load.

Barrels41 I will do about the same and try 35 35. The ride is acceptable to me at those pressures. I will watch the tire ware and try that for now.

Macallan21

I run 34 to 36 psi all around.. basically as close as I can get to 35.

I do notice a drop in gas mileage if the pressure is low 30 psi..