Well the day has (nearly) come and I must pay to continue playing.
I want to say that I am really impressed with how the stock Michelin's have held up on my 13 M5. They will be just shy of 28k when they come off on Thursday afternoon. That also includes 1 HPDE weekend at Barber Motorsports Park!
So as I wrote about long ago when complaining about BMW mph's vs Actual mph, I'm going to "up" the cross section ratio on the rear tires. I'll share back how that works out. I'm expecting good and uneventful.
Another indirect advantage is that though I'll be staying with 295s in the rear, I'll actually be getting an increase the contact patch (aka Tread width) from 11.5" on the rears to 12". The downside is I now am paying a "Ferrari-inspired premium" ($416) over the 30 series tires for BMW ($351).
Here is a link to spec information should anyone else wish to repeat:
Stock config:
265/35ZR20 (99Y) XL BMW
295/30ZR20 (101Y) XL BMW
http://www.tirerack.com/tires/tires....5&autoModClar=
35 Series rear:
295/35ZR20 (105Y) XL K1 Ferrari
http://www.tirerack.com/tires/tires....SSXL&tab=Specs
The Ferrari spec tires have a higher load rating than the BMW, but higher is acceptable (its when you go lower that you often get into trouble with sidewalls that are too weak). There is an SL Ferrari version (same 295/35 ratios) available as well that is actually very close to the XL BMW version's load rating but you don't increase any in the tread width.
Probably boring stuff to some, but I'm just sharing in case it may benefit someone else.