Originally Posted by HighlandPete
Increasing pressure reduces shoulder wear on run-flats, as you run on the crown of the tyre, not so much on the stiff sidewalls.
One of the reasons run-flats wear so bad on the shoulders is the tyres take longer to warm up to full working pressure, so more time at lower than ideal pressure. Lots of short runs make the situation even worse, tyres hardly ever run at optimum working pressure. I personally run a couple psi higher winter time, just to compensate for this fact and reduce shoulder wear.
I've always erred to the softer settings on my tyres and never experienced any edge wear. Most of my trips are very short. Mind you, I don't power launch off the line and increase my rear camber.
I had to juggle the pressures as I have Y rated 18" and they have a very different ride, load rating and suggested tyre pressures as on the door jam compared to the W rated 18" tyres. The Y spec tyres have much softer pressure settings.
I've found setting the pressure higher leads to a slightly more skittish and tiring ride. On my early E92 335D the dampers just don't seem able to cope with the increased, sharper jolts.
Either way, I hate RFTs.