I vary my BFGs. 44 in the winter for traction in snow, 35 in the summer for onroad comfort. Last year I tried 28, but that was a bit too soft, IMHO.
When I got the M3 I decided I favored my back more than high-speed cornering in the VX.
Find what you like, within reason. Try a few different pressures. Watch the wear on the tires. Uneven wear might mean early replacement, but comfort and performance both come at the price of treadlife.
-Daver