I'm a new '04 G35 Coupe Owner with OEM 17" 6-spoke wheels,F-225/50/ZR17, R-235/50/ZR17. Its my daily driver and I love it, but would like to accomplish the following:
1: A little more aggressive look
2: Better rear traction
3: Slightly tighter feel/handling with least affect on ride

I've found a set of aftermarket 18x8.5(F), 18x9.5(R)(35mm Offset on both) that I really like - based on my research, 245/40/18s and 275/40/18's seem to be a good/common fit.

I'm a 'tire aspect ratio' newbie, but have researched quite a bit and am a bit confused - based on my caculations, my current rears should be about 0.4" taller(diameter) than the fronts, but they're nearly a full inch taller - what am I missing?

This upgrade should have a slightly taller rear, and slightly shorter front than stock - is this correct?

Any opinion on this upgrade achieving my goals welcomed.

Also - what do I have to do to retain the tire monitoring system (I've searched a bit and will continue to, but if there's an easy answer - greatly appreciated).

 

The 245/40-18 275/40-18 combination would be the best to use. Outside diameter of the rear tire will be the same as oe, but wider. Your oe sensors should transfer over to the new wheels, just need the rebuild kits so they dont leak.

 

Agreed. 245/275 is a very common tire size combo.

 

Greatly appreciated - Just ordered the wheels, so tires are next.
Didn't know about the rebuild kit, so off to research that as well.

THX!

 

Rebuild kits are actually pretty inexpensive. It's a great way to save some money over purchasing new sensors.