[weingarm]

How many miles do you have?

I have about 3900 miles - don't notice much difference front vs rear tread wear yet. That said, I wouldn't be surprised if the wear difference you mention is typical for the M5. Even while running in normal "4WD" the torque is routed preferentially to the rear.

My last vehicle (Maserati Ghibli SQ4) routed torque 100% to the rear unless slippage was noted. I can tell you those rear Pirellis were done at 10k miles (12k miles was downright dangerous with even 1/4" snow!) The front Pirellis lasted 20k miles easily.

My plan on the M5 is this: I'm switching out the standard summer Michelin PS4s for Pirelli Sotozero 3s for November-March. They'll last 3 winters because I only drive about 3k miles each winter. The summer Michelins will go back on for summer 2020. After that they'll have 10k miles so I'll buy another full set for Summer 2021. Lease is done 3/2022.