The BMW recommended road tyre pressures for the std 18" wheels are 30 front & 33 rear. What should they be set at cold before going on the ring or at high speed on the autobahns?
on the autobahn, I`d leave them. On the ring, do a lap then check the hot pressures, letting some air out if necessary to get to your desired hot target pressure.
Remember to put air back in when you`ve finished at the ring and are driving home..
