I noticed a post on the board last week about checking your spare tire pressure. So I checked mine today and to my suprise, my Z had 5 psi and my wifes spare was completely flat. Both of these are the donut spare and are supposed to be inflated to 60 psi. (ok, ok, 61 psi for BMW, 60 psi for Volvo, but they are the same exact tire). I saw my neighbor out and he checked his donut spare, it had 12 psi. So, Check Your Spare Tire. On the Z3 (not the M), you should have an inflation nozzle accessible from the outside of the spare carrier.