many legacy specific info but im sure there will be similarities:
But to be on the safe side, here is the tire widths you can put on each rim:
195mm = 6.5", 7" and 7.5"
205mm = 6.5", 7" and 7.5"
215mm = 6.5", 7", 7.5" and 8"
225mm = 7", 7.5", and 8"
235mm = 8", 8.5", and 9"
245mm = 8", 8.5", and 9"
255mm = 8.5", 9", and 9.5"
265mm = 8.5", 9", and 9.5"
275mm = 9" and 9.5"
285mm = 9" and 9.5"
Once you decide on the rim size, the tire width you want to run, here are your final tire choices. Note that not all tires are built the same way, so sometimes you'll find two different tire models with the same size (225/45/17), but one can fit on a 7" rim, while the other one will need a 7.5". You'll have to look around the manufacturers' specs on sectional width of the tire.. normally you want your rim width be no more than 1.5" less than the tire's sectional width. For example, if you have a 8" wide rim, your tire's sectional width shouldn't be more than 9.5" or you'll have to deal with the flex on the tire sidewalls. Most performance driving set ups are 1" difference (ie. a 8" wide rim with 9" wide tire). Below I listed for you by rim diameter of which I recommend running with some notes on each tire with notes to go along with them as well:
16 in. rims (for 2.5i, 2005-on) only:
195/60/16 (great for snow rally or snow use)
205/55/16 (OEM sizing which is also good for some non-tarmac surfaces)
215/55/16 (oversized for the rim protection, but very sloppy sidewall handling)
215/50/16 (wider footprint used for more daily driving without harsh gas consumption)
225/50/16 (great for autocrossing, still usable for daily driving all year round)
17 in. rims (for GTs 2005-on):
205/40/17 (only for SUPER FAST acceleration and torque; for autocrossing only, do not use for daily driving)
205/45/17 (only for FAST acceleration and torque; for autocrossing only , do not use for daily driving)
205/50/17 (good for snow rally)
215/45/17 (stock)
225/45/17 (good autocross performance tire size for gearing, more mph per gear)
235/40/17 (good autocross performance tire size for torque, more acceleration)
235/45/17 (tallest tire you could use under the GT due to possible suspension clearance issues, best used with an 8" wide wheel)
245/40/17 (good autocross performance tire size for traction, will need to have a flatter alignment to make use of the grip)
255/40/17 (maximum grip, good for track days, will need a 9" rim to make use of the contact patch and a good alignment as well).
18 in. rims (for GT 2005-on):
215/35/18 (only good for autocrossing use, do not use for daily driving)
225/35/18 (only good for autocrossing use, do not use for daily driving)
215/40/18 (uncommon tire size, close to OEM overall tire diameter, good for daily driving)
225/40/18 (typical sizing, most popular size, GREAT for daily driving)
235/40/18 (very large, but great for pot-hole city driving, may need fender rolling)
235/35/18 (rare size, but closest to OE tire sizing to keep the spedometer reading correctly)
245/35/18 (common autocross, performance size, very good for daily driving)
255/35/18 (very good daily driving size, even better on the track)
265/35/18 (very good daily driving use, but the car wont be able to use all 265mm of tread for the track)
275/30/18 (tallest tire you can mount without fender clearing issues on a 2" lowered car if you get the right offset)
285/30/18 (aka, the "STREETS OF DREAM" setup... the widest you can go.. this is the next tire size I am going for and a rim to match it)
18 in. rims (for Spec B.2006-on, 3.0Rs 2008-on):
225/40/18 (common tire to use and gives a better acceleration since it's 0.5" shorter)
235/40/18 (rare size to find, but near stock height for proper gearing)
245/40/18 (popular tire size for the larger cars)
19 in. rims (for GT 2005-on):
225/35/19 (common typical sizing for 19" for our cars)
235/35/19 (tallest tire you can mount without fender clearing issues on a 2" lowered car if you get the right offset)
245/30/19 (rare size, but also tallest tire you can mount without fender clearing issues on a 2" lowered car)