Wheel Guys Chime In! Need advice on tire sizing
 

I'm hoping some of you that have been mounting multiple sets of wheels and tires can steer me in the right direction.

18x9.5 rear
18x8.5 front

1" drop on eibach pro kit

I know I want to run 255/35/18 in the rear, I've heard that wil fit fine (correct me if I'm wrong), what front size will fit without any camber adjustment or fender modification.
I'm not looking for the stretched look, I just want a tire that will fit without modification.
Thanks on advance for any help it advice!

do you know the offset of the wheels?

Yea sorry, 35 front 30 rear

235/40/17 front sounds about right.

18?

245/35 or slightly stretch a 225/40. i think the 225 is as tall as the 255 if I'm not mistaken.

Whoops!

I did 225/40 with a 45 offset 8.5 in the front and 255/35 with 45 offset 9.5 in the rear. Did an alignment check all was good and no rubbing.
I think with you dropping it and inch you still be ok. You might do 35 front / 40 rear?

Thanks for the input guys, my main concern is that it fits without modification and that it doesn't look weird.

Here's some comparison specs:

Stock Tires
Section Width: 8.46 in 215 mm
Diameter: 24.61 in 625.09 mm

235/40/18 <------- Hard to match the rears with good tires
Section Width: 9.25 in 235 mm
Diameter: 24.47 in 621.53 mm

225/40/18 <-----This seems like it may look stretched or too different from rear
Section Width: 8.85 in 225 mm
Diameter: 25.08 in 637.03 mm

245/35/18 <-----This seems ideal but there's limited tire selectiion
Section Width: 9.64 in 245 mm
Diameter: 24.75 in 628.65 mm

I think your calculations are off for the 234/40-18's, that doesn't jive with what I'm seeing.

I think 245/35-18's would be the closest match if you're trying to maintain a diameter as close to stock as possible.

Here are the tires I'm seeing as available in that size:

BFGoodrich g-Force T/A KDW NT
Bridgestone Potenza RE050A Run Flat
Bridgestone Potenza RE760 Sport
Bridgestone Potenza S-04 Pole Position
Continental ExtremeContact DW
Falken FK-452
Hankook Ventus V12 Evo (K110)
Kumho Ecsta XS (KU36)
Michelin Pilot Sport PS2
Pirelli P-Zero
Pirelli P-Zero Corsa System
Pirelli P-Zero Rosso
Pirelli P-Zero Run Flat
Pirelli Winter 240 Sottozero
Pirelli Winter 240 Sottozero Serie II - R.F.
Toyo Proxes T1 Sport
Yokohama ADVAN Sport
Yokohama S.Drive

Dont get the PS2's, Get the Super SPorts, just got those today.

@Foobar: You're right: 235/40/17 is Overall Diameter: 25.40 in 645.16 mm
Where as 245/35/18 is Overall Diameter: 24.75 in 628.65 mm
I'm really having tough time picking tires, I know tires very well, but I am very hesitant when it comes to the special circumstance of this car and what I want to use it for.

@Got3n I've been a Michelin/BFG dealer for 4 years, I would never get PS2s. I have been leaning toward Pilot Super Sports, but I have been considering G Force TAs as well. The car is not going to see much rain or snow, but I do want something that will stick once I go turbo and make a couple of 1/4 mile passes.

225 should be about the same amount of stretch on an 8.5 as the 255 would have on a 9.5 it should look quite similar IMHO