I think the stock rims on a 6 are 18x7 and +55 offset or something like that.
You could always have a look at mazdaspeedforums in the us to see what rims they have managed to squeeze on, I don't think I have seen any with +22 though. Also, word of warning, make sure you read and search everything on their forum before making any posts, especially if it asks something like which bov is best lol, they will tear you to shreds! You should also search this forum too of course but this place is much more friendly
AP V3 (Rayd tuned) / CP-E CAI / CP-E TIP / JBR Trilogy / CS Front Strut Brace / JBR SSP / JBR Shift Knob / JBR shifter bushings / Eibach Pro-Kit / Bilstein B8's / SURE Juggernaught / SURE Dreadnaught / Whiteline RSB / Toyo Proxes T1R 235/40/18 / Evo X BBS rims / Turbosmart Dual Port BOV / CP-E DP / CP-E TMIC / Autotech internals / Superpro bushings
Future mods:
BT, DM OCC, EGR delete, Braided clutch/brake lines, Hawk HPS 5.0 pads, DBA T3 rotors....