I have a g37x coupe, and looking to get these

http://unleashedwheels.com/catalog/product/view/id/11

Going with 19in

But I'm am really unsure about the offsets, tire size, etc.. I don't know much about tires or wheels, I've done a lot of research but im still not sure what to get, can someone tell me what tire size I should get with these wheels?

 

These look like knock offs of rays te37s. I've never heard of this brand before. And like so many new G owners they want to get new wheels at the cheapest price. I was one of those people but never came around to spending the money on knock off wheels. I'd advise you to do the same. Save your money and put on some bolt ons for now. ei: cold air intake, cat back exhaust, high flow cats, etc. I prefer that my car runs faster and is more responsive than what I'm rolling on. I've done most of my bolt ons so far. Now I just need a tune. Lastly will be the wheels. I'm hoping to get "authentic" volk re30's 19s.

Oh btw... I also am a X coupe owner, do consider dropping your car, bc the ride height is such an eye soar. We drive a sport cars not an suv.

But.... If you won't consider anything I've previously said, u should get a squared setup for you wheel widths. That means all 4 wheels will have the same width. I'd personally go with a 9 to 9.5 width. Wider wheels make the stance look aggressive. As far as the offsets I'd go with either a 22 to 25 offset. This should make the wheels flush with your fenders. I hate the sunken in look. And since u have an X I'm assuming you don't have a BBK yet, so u won't have any issues with that.

As an X driver you have a few options on tire sizes. I run 225/45/19 with no problems at all. You can also run 245/40/19 with no problems. Just remember that you have to keep the "rolling diameter" within 3% of the stock rolling diameter of the car with the 18's on. Failing to do so can f' up your AWD system.

Hope that helps.... Stay away from knock offs. Lol

 

Welcome to the site!
It appears those are only available in 9.5 to 11" widths, going w/ 9.5s all around w/ a +30 offset I'd run 245/40/19s or at the most 255/40/19.
Your stock wheels should be 18x8 +43 w/ 225/50/18 so using this calculator will show you how they'll fit~
https://www.myg37.com/forums/tire_rim_calculator.php
You'll extend out from your current set by 32mm, if this is the fit you want then it's a win, just be sure to measure carefully as the inside fender is easy to hit when you get tight. Only run the 255s if the 32mm
extension still leaves you about 7mm room.

 

Here's a similar looking wheel but it's a quality well-known brand, I'd pay a bit more for these
TreadDepot.com: SSR GTV01 Black Wheels