Originally Posted by
z06ontrack
It appears you did some homework when you changed tires. you have to remember that the PS4s are dual compound (hard in the middle, soft on the outside) and many things affect tire temp, especially toe and camber. I'm not going to suggest you change the pressures that feel correct for you but, if you ever track the car or drive hard (cornering) you want to keep the hot pressure below 32 psi on the PS4s.
I do track the car. I used to modify pressures before going on the track but eventually learned to just start with my street pressures. I may let some air out on really hot days, but never as low as 32 psi. Even Michelin says the ideal pressure for the PS4S tires on the track is 36 psi, but that is just a general recommendation across all tire sizes and all makes and models of cars. However, there is no "one size fits all". Weight distribution and suspension geometry differs with each make and model and may require different pressures. Driving technique and level of aggressiveness in corners can also impact the ideal pressures.
Tires are the only point of contact with the road and they are the starting point with any effort to maximize handling. The goal is to have the correct amount of air in the tire to keep as much of the tread as possible flat against the road surface with equal pressure across the tread surface. That is the only way to get the most out of your tires, and the most traction your car is capable of. If the tires are under-inflated the center of the tire will exert less pressure against the road, the outside edges will wear faster than necessary, and you will have less traction. If the tires are over-inflated the center of the tread will carry more of the load, they will wear faster than the outside edge, and you will have less traction.
If you have a pyrometer, you strive for equal temperatures across the tread surface. If the center of the tread is hotter than the outside edges, the tire is over-inflated; if the outside edges are hotter, the tire is under-inflated. If you have hotter temperatures on the inside or outside edge of the tires, then tire pressure alone won't give you maximum traction and you may need to consider alignment changes and/or modified suspension components.
In addition, there is a simple way to determine inflation on the track without a pyrometer. Performance tires will have a marker on the sidewall to indicate the ideal amount of sidewall involvement in heavy cornering. It will be roughly 1/2 inch down the sidewall from the flat tread surface. Drive aggressively then check the sidewalls (you can even mark the sidewalls with something like chalk). If your sidewalls scrape below that marker you are under-inflated for how you are driving. If they don't scrape to that marker they are over inflated for how you are driving.
My 2019 RS5 SB needed 39/32 with the oem Continentals to provide the correct amount of scrape on the track (e.g., Road America). The PS4s required higher pressures and I like 41/35. I should point out that Audi recommends 41/36 if you intend to drive above 155 mph, so I don't really see 41/35 as being unreasonable. Also, with those pressures I get slight understeer in Comfort, neutral handling in Auto with the ability to induce some oversteer with the throttle, and oversteer in Dynamic.
These photos show the sidewall marker on my PS4S for both the front and rear tires. The front tires had 41 psi cold and the rear had 35 psi cold. The specific marker will vary from tire to tire, but it serves the same purpose across tire brands and models:
TirePressureFront-33.jpgTirePressureRear-33.jpg
Reply With Quote
Bookmarks