We have a lease so I didn't buy spare rims, we just got some winter tires and swapped them out at Pep Boys in December, swapped back to all-seasons in March. I had read all kinds of warnings about making sure the installers don't mess up the TPMS, so was a little nervous. Turns out Pep Boys did a great job, no TPMS errors or warnings, and the tires were great. Drove from LA to Tahoe 2x last winter during crazy snowstorms. No slippage problems at all.
The tires were Dunlop Wintermaxx 2. 245/45/19. Go ahead and make fun of me for not buying the Pirellis, but I only paid $125/tire and they handled great.