Actually, increasing tire pressure will create a harsher ride.
I’ve seen an AMG Driving Academy video that explains why Mercedes AMG cars run on very low tire pressure (27psi).
They created a demonstration with a German dude and two tires. One tire was at 27psi, the other was at 35psi. He was explaining that traction and control is reduced with the higher psi, and demonstrated this by picking up the 35psi tire and dropping it from 6 inches to a foot in the air. It bounced several times. Then he took the 27psi tire and dropped it from the same height. It basically hit the ground with a thud.
The demonstration was designed for AMG drivers – so that they get the maximum grip and handling by inflating to the proper psi.
If you inflate your TDI to 35psi, that’s the ideal pressure to which the car was calibrated. If you go lower or higher, the ride quality will be affected. MPGs will also make a difference as well.
I always stick to the label on the door.
There is a video on the autonetwork where a man from Audi is riding around the back of a Q7 TDI explaining that VW/Audi did extensive testing in the US for the TDI and found that diesel fuel quality was absolute crap when compared to Europe. He said that minimum cetane in Europe is 52 and in the US, each station at any state had levels mainly around 35, but would fluctuate to the 40’s and nothing was consistent.
Basically, quality diesel fuel is the issue at hand, not tire pressure.
