Hi, Rich and Janet Bentley here. Am new to the club. Bought a 2007 Z4 a couple of years ago and really enjoy driving it. Have just over 18k miles on it and took a nail in one of the tires. Decided to replace all four. Abandoned the run flat tire for the Michelin Pilot Super Sport. I have to say that the car really came alive with the Michelin. Quiet, smooth, and road holding that seems superior to the Bridgestone Potenzas. The car no longer chases irregularities in the pavement, especially under braking. These tires generally inspire even more confidence than the Bridgestones. The question: Should I modify the tire pressures from that recommended for the run flats (35psi front, 37psi rear)? Has anybody else made this change? And did you find a better pressure to run these tires on? Thanks!
Welcome to the group! I switched to PS2 on my e46 touring and share your sentiments; nice improvement in handling, ride and noise. But I was not coming off of RF tires as you were. I have tried a few pounds up and down from factory setting on these tires and notice a crisper ride when more than about 5 lbs higher than spec. Not exhaustive data - only been on them a couple months so far.
On my roadster, I inflate to 38 pounds cold. When autocrossing, I drive the ten miles to Qualcomm and then DEflate to 38. Seems to work okay on BS RE-11s.
Like most would say - tire pressure setting probably can range up or down as much as 10 psi, depending primarily on what you are comfortable with. Low setting minimum will be prescribed in manual or on the door post. My Z4 M with stock Continentals handles just great for open road fast driving with the 30 psi recommended by BMW. The car is an alert handler so it was likely designed for this pressure to provide M car response for a M car road driver. If I inflate them to 32, the compliancy in bumply roads starts to go away. Another 2 psi and the suspension loses its compliance and would be only comfy on a very smooth road. I sold my 2007 3.0i after fitted 4 RE11's. But for the short time I had the car with those tires - I was blown away by the change from run flats. BMW engineers (other than the M guys) are designing for committe by comittee - in regards to many design decisions - and run flats are one of the worst! (EPS is another!) My 2001 525i feels like what it is supposed to feel like (quiet and comfy, but fairly crisp with good road manners) when the new Firestone Indy 500 tires are inflated to 31 and 33 (high payload settings).
