I'm in the market for some new tires, since I got this G37 used I wanted some fresh new tires. The stock tires are 225/50R18 for all tires. What is the best for the rear of the car I've been told 245 for the back.. Can anyone help me out? I've never really bought tires especially for a sports car. I want the back tires wider than the Stock 225/50R18 with no problems. Thanks!

 

Why exactly is it that you want wider tires in the back? Is it just for looks? . . . handling performance? . . . or what? Are you aware that a 245 width tire is not appropriate for the width of wheels that you likely have? Or that, even if they were wide enough, that it would likely handle worse with them on the rears only?

If you want a staggered setup, then you should be running it on a properly staggered set of wheel widths, and even further still, you should really have a properly tuned suspension to match the handling bias you will be adding to your car. Additionally, if your car is an X model, then you introduce a whole other set of concerns regarding dissimilar sized wheels in the FR vs RR.

Make no mistake, you can cram a set of wider tires on the rear of your ride and "get away with it" just fine (as many have before you), but you should at least know and understand what is appropriate for your setup and what exactly you are potentially compromising should you make the change.

.02

 

Thanks for the input, I just want something a little wide, or in terms wider than the front tires, I have RWD.. I just thought it would look better, since my buddy has a Lexus IS350F and his back tires stick out a little more than the fronts making it aesthetically looking better. So should I just stick to the 225/50R18?

 

VQ speaks the truth
The 245/45/18 minimum recommended rim width is 8" and max 9.5", your 7.5" rims would result in a "pinch" mount that can cause the sidewalls to roll under hard cornering, resulting in poor performance and handling that can be unpredictable at speed.
If you want a more aggressive look with a wider stance you could put money toward a set of 19" coupe wheels. These wheels are 8.5" front 9" rear that can accommodate a 245 front and up to a 275 rear. You can find sets in our classified section for nice prices.
I'd give this page a good read, there's also a small 1 line calculator about 3/4ths down the page called "An Ideal Rim width calculator" that will show you what rim widths will work (a standard mount) with any tire size.
Car Bibles : The Wheel and Tyre Bible

 

I would say that for the rims and suspension tune you have, you would do well to stay with a "square" setup, i.e. same size tires front and back. Given that your rims are undoubtedly the 7.5" width, I'd say a 235/50-18 would be your best compromise between handling, wider "looks", and minimal speedo/traction-control error. Now you COULD go up to a 245/45-18, but it should definitely be on all four corners (NOT just the rears), and it would definitely be sacrificing handling for looks, since the tires are too wide for the wheels then. Speedo/traction-control error would be nil though.

Incidentally, you need to find something better to worry about than how your buddy's Lexus looks. OOPS, did I just say that out loud.

 

Thanks for the inputs fellas, I just went on ahead and ordered the 225/50R18 Michelin Pilot Sport AS/3 Tires for all 4 wheels..

 

^^ That's a good set of tires and a perfectly reasonable choice.

PS. Remember, you'll be able to rotate your tires and get maximum life out of them, long after your friend's staggered setup is shot.