[35th ed/ed]

Looking to go down a wheel size or two if posable. Have a '09 GXP which have the 18 inch wheels. Would like to go down in size to get a taller tire due to the potholes during the winter. These are for the winter months only as the G6 is primarly used by a new driver in the family.

 

[360ci]

I believe the GXP has larger front brakes. Check with the dealer, but I'm almost positive 17" wheels would fit fine over the brake calipers. I don't believe 16" wheels will fit without problems. Keep in mind that the interior dimensions of an individual make/model of a wheel can vary. I found this out the hard way on one of my older cars.

 

[CalsGTP]

Just ordered a set of 16" steel wheels and 215/65/16 blizzaks from Tire rack for my 06 GTP with the 18" wheels. They say they will fit and I believe them because the rotors are the same for the any G6 with a V6 so I would say your GXP will be the same. Tire rack shipped to my house was $707 and I got a $50 rebate coming to me yet!

 

[35th ed/ed]

Took a look and the 16's look to be tight as the fronts are larget.

As for Tire rack I would rather pat more to get what I need instead of what they want to sell. On thier behalf they did take the wheels back that I ordered for the truck but wanted to charge more for shipping on thier mistake.