It seems that most people have opted to change their tire sizes to 235/50/18 front and 255/45/18 rear. Is there a reason why we should get a different size on the rear than stock. Most manufacturers have our rear size available.

Michelin has the Pilot Sport A/S Plus in both the stock rear size and the 255/45/18's. Does anyone have any experience with this tire.

stock sizes are harder to come by than those when it comes to alot of other tire brands, plus some people like the extra meet.

So I can get the stock size rears with the 235/50 fronts?

The 235 fronts will be 27.25" versus 26.85" (stock 225s) which equates to a 1.47% difference in speed (not too bad).

I would get a larger size rear tire for the rear personally, since it seems there's less protection for the rim on the rear versus the front.

It's best to keep the front to rear relationship the same.
If you increase the front, do the same to the back.

It's the diameter that matters.

I was considering getting the Michelin PS2's. They only have stock size available for out for the G35s. 255/45/18s aren't available. I'm having a tough time deciding between the Goodyear Asymmetric's, PS2's and the PS A/S's. I can get the Asymmetric's and the PS A/S's in 235/50 and 255/45, but the PS2's I would have to go 235/50 and 245/45. Opinions?

I have the Eagle F1 A/S's on now, but at the 5k mark all 4 are badly cupped and the store was able to get a full refund from Goodyear to apply towards new tires.

Goodyear asymmetrics are crap. Get the PS A/S plus, great all season performance tire.
-GP-

Alright, I pulled the plug a few moments ago. Very tough decision between the PS2's and the A/S Plus's. We generally don't see much snow in VA and I'm not going to drive my car in the snow anyway, but we do get some extremely cold weather for 3-4 months of the year. The stock Bridgestones would slip and slide near the freezing point. I decided to go with the Pilot Sport A/S's. I hope I'm not disappointed in the handling. While I'm normally just commuting to work in the G, it's always fun to push it on the twisties and the on/off ramps. The F1 A/S were horrible for cornering in my opinion. They did not instill confidence like the stock rubber. The Pilot Sport A/S's have numbers pretty close to the stock rubber according to Tirerack's tests.

Cool, let us know how they are. Per our PM convo, am not a huge fan of the Asymmetrics - they're fantastic in wet conditions, but only decent-to-good in for sport performance in the dry. Will probably go Pilots next, but wish they made PS2s in 255/45/18

I don't understand why they don't have that size. The original Pilots did. I've never been a fan of Goodyear. I tried the F1's based on the favorable reviews I read, but as usual they were a huge disappointment. The Asymmetrics have received some fantastic reviews by many different review places, but from reading the many high performance car forums the PS2's are legendary. As much as I hate to buy French goods, I have to say they make the best damn tires. I've never had problems with Michelin's! While the PS A/S's are a compromise, they too receive very high praise in all the forums.