Winter wheels are on! I bought these TPMS sensors, part number F2GZ-1A189-A. I had them mounted up at the tire place and had some Blizzaks put on the M3 at the same time. I could fit all four bare wheels in the trunk of the MKZ at one time, but with the tires installed, I could only fit a single wheel in the trunk, so I had to put a couple in the backseat of the M3.
Goodbye stock 21s.
I started swapping the wheels over, only to find out that the trunk of my MKZ wouldn't open, which is apparently a thing that happens.
And the only manual release is actually inside of the trunk. I did the battery disconnect sequence recommended in the owner's manual but it didn't help. I had to just pound on the button for a while and finally the trunk popped open and I could get the MKX tire out.
Tires installed, they're a 245/60R18 Blizzak DM-V2.
I dropped the car back on the ground and torqued the lug nuts. Then I used this TPMS-19 programmer to teach the car the new sensors.
Immediately I noticed a decrease in steering effort vs. the 265-width 21s. The snow tires are definitely a bit more squirmy when turning, and there's more noise at highway speeds, but they're smooth and the car rides great. I did find a hill covered in solid ice to test them out, I'll have to post that video. It clawed its way up the hill pretty well, and the traction control actually let it get quite a bit of wheelspin after a few seconds. When the trans shifted to second gear, it really seemed to take off.
Pleased so far.