2009-2010 Vibe 2.4L Base/AWD/GT OEM wheel/tire specs:
- You can fit 16"+ wheels. I don't know of anyone that has gone past 18" wheels yet.
- As you already mentioned, the bolt pattern is 5x114.3
- The offset is actually +39. The higher the offset past +39, the more the wheels will "sink" into the wheel well. The lower the offset past +39, the more the wheels will stick out of the wheel well.
- The width of the OEM 2009-2010 Vibe GT wheels is 7". I believe it is the same for the 17" wheels and, someone please correct me if I'm wrong, but I believe the 16" steelies are 6.5" wide.
- The factory tire sizes are 16" = 205/55/16, 17" 215/45/17 and 18" 215/45/18
As far as getting the right tire size, etc. Tire Rack
is a great place to start. Enter your vehicle information and they will bring up wheels and tires that will fit your Vibe.