FWIW, I spent some time yesterday researching winter wheels and tires. I have the Performance Pack.
1. For years, on all my cars, I've had two wheel sets: one for summer and one for winter. It's easy to swap the wheels with just a few basic tools: jack, breaker bar, the right socket, anti-seize, and a torque wrench.
2. The PP cars come with summer tires. That just isn't safe around here from November to April.
3. I couldn't find 3rd party rims that would work. This isn't surprising as there's just about 0 clearance with the OEM wheels over those Brembos to begin with. I'd be very skeptical of any aftermarket wheels. Imagine wrecking your calipers with rims that don't work!
4. Here in the U.S., they're not yet set up to send out winter wheel sets to us. I could push for this, but it's easy to imagine it would take over a month.
5. A nice support guy, not Mike or Alane... probably a Volvo guy covering the phones... dug around for me... It looks like a winter wheel package would run about $5000. That's believable to me.
6. I located a number of tires that would work and can buy them online and have them delivered to a local shop to have them swap the rubber on the existing rims.
7. New tires need to be 245/40 R20 XL. Remember our cars are heavy so you need that XL designation. XL tires also need higher tire pressures. Hence the 41 psi front/42 psi rear (280/290 kPa) recommended pressures.
8. Our wheels are big and sidewalls low, so some local mechanics might struggle with the swap. Have a chat and try to feel them out about the job. I'm having the nearest Volvo dealership do the swap as they're more likely to have the right equipment and this is a way to get to know the local Volvo service people.
9. You should let the mechanic know that the rim widths are different front and back but the tires, oddly, are the same size front and back. They should be aware that you're aware. It's an unusual way to do things.
10. Possible good choices (my opinion, not exhaustive) that I've identified in the U.S. are as follows:
a. Continental ExtremeContact™ DWS06
b. Nokian Hakkapeliitta R3
c. Pirelli Winter Sottozero 3
11. These are all pricey tires. But I think tires are a good place to invest money.
12. I went with the Pirellis at a total cost of $1440 for four. Installation and balancing was quoted as $140 for all four.
13. You may hesitate to spend extra money on winter tires but realize that when one set is on, the other set is not being worn down. So you're not losing any money on the extra rubber at all, with the exception of the installation charges.
14. Don't forget that stopping distance with winter tires can easily be less than half that for summer tires. This difference might actually save your life or those of others.