I have no doubt the fit is good, it's just outside the recommended rim width for that 225 size.
The DWS in that size recommended rim is 6-8", so another 1/2" isn't a deal breaker IMO
Just click on the "view more" tab once you scroll down to the specs
http://www.continentaltire.com/produ...22550r18-95w/?

I use this little single line calculator on this site, it's about 4/5ths the way down the page, but depending on brand/model of tire that range could be wider or narrower than what this calculator suggests, but is a good baseline
It's titled "An ideal rim-width calculator"
http://www.carbibles.com/tyre_bible_pg4.html

 

Sure, it's a softer compound, not really made to be driven aggressively.

Once winter tires are about 50% worn, their snow traction diminishes greatly. The treadblocks are no longer there to bite into the snow. I paid an arm and a leg for the wheel/tire combo (to the tune of almost $1200) so getting as much life out of them is more important than the enjoyment I get from driving in the winter. I have the xice2 model. They're ok in the snow but will still go wide in a turn on several inches of fresh snow. AWD would do better, but I can live with this.

 

My local tire expert thinks the 225/50R18s should be no problem on the wider rear rim, so I think for simplicity, and until I can spend time finding the right aftermarket rim, I'm going to pick up the 225/50s locally before I head out next week to pick up the car. The dealership can mount and balance them when I arrive. I looked into getting tires from them,but they had trouble getting Xi3s, and really wanted to sell me other tires and packages I didn't want, so I'm more comfortable arriving with the tires. 850km up, 850km back. Wish me luck and thanks for all the help. I'm sure I'll need more!

 

Momentum guys.......

 

Good choice. Exactly what I would have done. No point in wasting money on rims that you will use in the winter when you can just use the stock rims. Especially, when you plan on getting nice rims for the summer.

 

Thanks for all the advice. Happy new owner of a 2012 G37S 6MT with 225/50R18s on oem staggered rims. 1200 km drive home yesterday before the snow . This is she this am. Beautiful, eh?

 

hmm, might be best to leave the G as-is for the day!

 

Nice! The white/gray two-tone fade paint job is rare.

 

Thanks for the info! I'm getting my winters put on today, same sizes/staggered wheels as you. I was a bit leery that the rears are wider than the recommendation, but it looks like others have had a good experience with this setup.

 

That setup worked fine all last winter. This season I've put a set of cheap aftermarket Touren winter rims -18"X 8" all round. Last years XiceIIIs working great and no trouble fitting over the front calipers. I just like the idea of having dedicated winter wheels.