the guy had 245/35 on there already and it doesnt look so bad, and i check tire rack they recommanded 245/35 for 19x9 so i figure it'll work

 

a 245 is the perfect width for a 8.5" wide wheel...
a 255 is the perfect width for a 9.0" wide wheel...

a 275 is the perfect width for a 10.0" wide wheel...
a 285 is the perfect width for a 10.5" wide wheel...

...if you want to maintain the stock stagger on your G.

FYI, I'm running a 19.0 x 9.0 (+25 offset) with a 255/35/19 and a 19.0 x 10.0 (+25 offset) with a 275/35/19 AND I'm dropped about 3/4" all around. I personally would not run a 245/any number smaller than 40 on a 9.0" wide wheel. For the G that would totally hose up the car... VDC would hate you!

 

so if i run 255/40 front and 285/35 rear would be fine without rubbing problems and clearance..? also im not dropping the car so it's gonna be stock height

 

255/30, 285/30. I don't know how many tire choices you're going to find with a 30-series profile, but if worse comes to worst get 255/35 for the fronts. But 255/40 no way. It shouldn't rub if you keep the stock height, I've seen a Z with 305's in the back and he said it didn't rub at all, no spacers nothing. Btw what part of Miami are you in if you don't mind me asking, that neighborhood looks REALLY nice.

 

Spend a few minutes with this calculator and see what you think... Tire Size Calculator.

Make sure to read the results of the varying sizes.