Originally Posted by nikitino25
For those of you with the current performance suspension, have you switched to non run-flat tires? I'm thinking about getting the suspension but I want to go with non run flats; would the suspension be too soft since it was probably designed with run flat tires in mind? Or should I not worry about that?
I can tell you this... the PS is not designed for runflats based on my butt sensors and track. I am using PS2 RFT to wear out and will replace them next spring with non-rft. You will feel almost every bump with RFTs. Think of the combo as RFT^2.
Assume that you will need to replace subframe bushings at the same time otherwise the rear will not feel connected to the chasis the way it should be. This is how e90 sport should have come from the factory and now we are paying extra to fix it. BMW engineers must have been so annoyed with bean counters and finally they were allowed to deliver.
I am getting Apex ARC-8 9.5 17in square and will run 255/40 tires. Currently PSS does not have this tire but PS2 is available and Porsche use it also. It is non-RFT of course and I think this will complete the setup with M3 subframe bushings, M3 bits, LSD and camber plates. For track this suspesion will shine with the R compund rubber in square set-up. Also, do not use M3 sway bars no matter what most folks on this forum say (personal engineering feedback). If you do all this the transient responses will be completely changed, meaning better control and stability, chasis and steering feeback, etc. - completely different animal.