So here's my plan.
As I mentioned, oem size for the CX-90 PHEV is 265/55R19, also an oem M-B size with M-B prices ($425/tire at Costco, before rebates). 19" wheels are $250+ also.
Going -1 with 18's is a bit sketchy due to the lack of knowledge on this new application. But -1 gives access to more tire options. Typical Mazda, all three oem fitments (18, 19 and 21") have non-matching tire sizes. So I can't use the base GS' 255/60R18. Doing the math on a tire diameter comparator renders 265/60R18 to match my 265/55R19's diameter. Same thread, but more sidewall.
The CX-90 MHEV comes with 18" wheels, but even the dealer has no idea if the calipers are larger on the PHEV. PMC Tire guarantees the fit, so they'll take the bullet if the wheels don't fit. Quattro/Pneusàrabais does not offer 18" fitments for my car, so no guarantee.
I like the DTD Blizzard. It's an "oem direct fit", is narrower at 7.5" so more curb rash protection. PMC has it at $196, but Quattro sells it at $169 and PMC matches prices. Win-win.
Tires now. My go-to is always Blizzak, my avoid at all costs is Michelin. However, the DM-V2 Blizzak for SUVs is so-so from presser experience - it rendered a Subaru skittish in the snow... Love the WS-90, but that ill pairing stayed in my mind.
Lately, Pirelli snows have always been great, from daughter's Accent to an X3. Blizzak is $325, Pirelli Ice Zero is $287. So I think I'll go with the Italians.
As for tpms, with all the tech in this thing I will bite the bullet and get them.
Entire kit mounted and balanced "free" and shipped to my door, also "free".