PR4's normally 34F and 38R (when cold!) - Up by 2 if on long motorway trips and with pillion and luggage.
Pro Twins suggest 31psi front and 34psi rear solo. They will set the tyres at this pressure if they service your bike. It will wear the front tyre a bit more but the better handling is worth it.
Gonzo - 31/34 will not give you good wear on the front or rear! PR4's get hot and start cupping at lower pressures. I talked to a Michelin man at PT and he recommended upping the pressure to 34 /38, the wear rate is less and you wont notice any less grip. My last 2 sets of PR4's have been fine at 34 /28.
