Been running cars here in SoCal 275 square with GT3 front bar and stock rear bar on stock PSS9's.
Also have ran R6 Hoosiers 245 square on 17's with GT3 front bar and Tarett 4way rear bar. It works well.
Few weeks back I tested 225 R6 square on a BoxsterS race car at AutoX. This place (Qualcomm) eats up A6's (the tires overheat with their 1.5 mile **AutoX's**) so I wanted to test a smaller R6. It worked great
Instead of the A6 being heated up within a few corners, the R6 took a full lap+. This meant the tire was good to go for the way they run their timed runs (no cool down time)
Every question about suspension and tires is dependent on the driver and the conditions. 99% of this world find a compromise that works for them (It may also work for other people) but you need to find what works for YOU in your situation.