The biggest rims u can fit !

 

My mistake, I meant the price is per car lol

 

I've got 21" summers on my 08' GTS and I switch to 18" wheel and tire setup in November to May. The 18" are just sweet in the massive Sierra blizzards, and have no problems at all even in the horrendous road conditions of last year.

On our 2011 S, we opted for the 21"s mainly due because we didn't get the air suspension, PTV etc...and figured it would boost the handling a bit. The only negative, is that you do have a bit of a gap without being able to lower the car with the air suspension. So it definitely has a more SUV look. With this car, I'm just going to switch out the 21"s with winter ones for the season as the GTS will be the main snow vehicle.

 

I would do 20" for all around, and later on switch to a 22" set up (aftermarket), if that is something you would consider. Usually, 22" tires are easier to get and less expensive.