I am new to this forum but have owned my G37 Conv since they first came out in 2009. As I am looking for new tires I will be going with Hankook V12 EVO but want to confirm I can go to a different size without affecting performance.
Any thoughts on me going from front - 225 50 18 to 245 45 18 and rear - 245 45 18 to 255 45 18?

Any thoughts or suggestions you have would be greatly appreciated. Of course tire dealer said it is absolutely fine and will not affect or change my performance.

Thanks for your help.

Front: P225/50R18 , Rear: P245/45R18 are your standard you s/b ok, - you can double check here:
http://www.1010tires.com/Tools/Tire-Size-Calculator
Make sure the clearance around wheel well.

Hi there. New owner here of a 2010 vert. Just purchased in Oct 13. Was on it's OEM tires (with 30,000+ miles, ouch) and knew I would be getting her 'new shoes' right away. I am also a HUGE FAN of the Hankook Ventus V12 Evo's...I run them on my Mazda6 sport sedan and have been VERY pleased with their performance, quietness, and cost.
Was very sorry to learn they are NOT produced in OEM sizes for my newly acquired G37
I also was advised by my tire shop that I could go to a slightly wider Hankook Evo on each end without degrading performance. He recommended 245/45/R18 up front and 265/40/R18 out back. I thought about it seriously for a bit. Since I have the 18" 5-spoke wheels (and I generally feel like the wheelwells 'fill up' better with the 19's on board) I was concerned that dropping to a narrower sidewall by 5mm per end would leave too much 'gap' around the wheels and the wheelwells. Also, mounting a wider-than-stock tire on my stock rims was a concern...but, again, the tire-pro assured me that the 8" fronts could easily accept a 245 width, and the 8.5" rears could have 265's with no fear of deforming the sidewall or 'tucking' the tire too much.
However, in the end I went with stock sizes of Conti ExtremeContact DWS tires. I hope I am as happy with them as I know I WOULD HAVE been with the EVO's which I already know I love.
Still, maybe I WILL try the Evo's at the next change...I know I would love to see some 265 rubber as I approach the car from behind, ha.

congrats on you new ride. post some pics, I have 09 vert.