I'm currently running 225/40R18 and 255/35R18 on OZ Ultraleggeras (18x8 +48 front and 18x9 +55 rear). I would like to run 245/40R18 front and 275/35R18 rear. Some questions:
1. Can I run this setup with just rolling my fenders?
2. If not, getting Shine wide fenders (+25mm) up front and rolling the fenders in the rear should be fine right?
3. My other concern is with the tire diameter as these tires are going to be about an inch larger in diameter than stock (according to tire size calculators): 25.7" vs. 24.6" stock front and 25.6" vs. 24.7" stock rear. Will this be a problem with my VSA or cause rubbing issues?

The reason I picked these tire sizes is that I can get the tires I want in these sizes (Star Specs, RE-11, AD08, V12s). Anyone else got other recommendations on other tire sizes or what setups you guys have?

 

What about 235/40 and 265/35? It seems like a decent compromise, should work with just a fender roll. I think at least the Star Specs and RE-11 are available in those sizes.

 

It's getting closer to tire buying time (been sliding around in the rain recently) and I think I'm going to go with your suggestion 1nate7 (thanks!). My concern with the 235/40 and 265/35 size is the over diameter. Take a look at the size differences vs. stock:

Front (stock 17" size/new size) in inches
Sidewall Height: 3.81/3.7
Section Width: 8.46/9.25
Overall Diameter: 24.62/25.4
Circumference: 77.34/79.8
Revs per mile: 819.24/793.97

Rear (stock 17" size/new size) in inches
Sidewall Height: 3.86/3.65
Section Width: 9.65/10.43
Overall Diameter: 24.72/25.3
Circumference: 77.65/79.49
Revs per mile: 815.98/797.06

My questions/concerns I still need to get addressed:
1. Will the new tire sizes set off my VSA?
2. I'm going the overall diameter for the new tire sizes are about an inch bigger than the stock tire size. Aside from the known impact on my speedo, will this have other impacts? Will it rob me of performance?

 

With the OZ wheel I would not go past the 225/40R18. I would alos not go beyond the 255/35R18 on the rear without modification. If I can help with the tires and or wheels let me know.

 

Thanks for the reply Jim. I'm going to roll my front and rear fenders so I'm not worried about the rubbing (should've mentioned that).

Any other issues with the larger diameter tires? VSA impact? Performance impact?

 

VSA shouldn't be a problem but you might notice the car is bit more sluggish. You are going to be increasing rotational mass and effectively running taller gearing with an oversized tire. It's up to you whether it's worth it for the extra grip, really 225/40, 255/35 is a near perfect combination for your wheel width.

 

On my track wheels I am currently running 255/40/17 up front and 275/40/17 in the rear on my car. I have flared front fenders and ASM rear over fender but the offset of my wheels is more aggressive than yours as well. 17x8 front and 17x9 rear with 35 offset all around.

 

Nice, thanks for the info! You're more than 1/2" bigger diameter in the rear (almost an 1" bigger than stock) than the front...notice any changes to the handling characteristics? Noticable performance degredation?

 

No reason to run a 275 when a 255 will do. I have the same wheels (only mine are the superleggeras) and I am lowered. I run 225/255 tires, and my front rubs on deep dips, and the back catches a little on the bumper tabs. 275 tires are just more expensive, heavier, and will NOTICEABLY slow your car down.

 

The 275/40/17 were the same rolling diameter as the 235/40/18 I run on my red advans, so all I noticed was the increase in grip. The 275s were $5 more a tire than the 255 I used on the front of my car. Keep in mind I have 4.57 gears so my car still accelerates great with the larger diameter tiers.