I have a 2003 G35 coupe. I have 20 inch rims that I want to put on. The rims are 20 X 8.5 with 35mm offset. I want to put 245's on 255's on the front. What is the biggest profile I can fit with a 245 tire or 255 tire? Will 245/40/R20 fit or 255/40/R20 fit?

thats not even the right size for the rear, you need to run 30 series in the width on a coupe. 245/30/20

No way is the 40 series correct with 20" wheels front or back, S/B 30 series.
Gary

I run:
245/35/20 front with 20x8.5 wheel
285/30/20 rear with 20x10 wheel

Anyone else think his offset is high... My offset is +30 and its close

damn 35 offsets, how do u get offsets bigger than oem?

Whoever told you those were the correct sizes to run on a coupe was very wrong. Your front tire is 1" taller now than stock

OEM 19's: (fronts smaller than rear by .7")
F 26.1" dia w/225/40/19
R 26.8" dia w/245/40/19

My Dunlop SP Sport Maxx: (F/R almost equal dia .2" diff)
F 26.8" dia w/245/35/20
-they don't offer 245/30/20 which would be a tish smaller and closer to oem.
R 27" dia w/285/30/20

What's wrong with running very close the same dia tires on F/R?
What's the advantage of running slightly smaller dia tires in front than rear like oem?
Just wondering why my front size is 'very wrong' in your opinion.
Thanx.

the oem profile is 40? really?

my tire is

front:235/30/20 - 20x8.5
rear:245/35/20 - 20x10

When they're replacements on oem width wheels yes 40.
Tirerack.com is your friend on all that stuff including alternate tire sizes due to different wheel dia and/or wheel widths.

Happy researching everybody...

i wouldnt really get a 40 profile, thats a lil too much