Been reading the forums for a while now, caught the mod bug and was thinking of getting some new wheels. I was wondering what mpg you guys that have upgraded your wheels to 20s and 19s are getting now, specifically for sedans. Was thinking about some Vossen cv4s, which are on the heavy side, but if the mpg suffer too much I'll look for something lighter. Appreciate the help.

 

If you plan on lowering your G the 20s look nice, if not the 19s will be a better fit. I've got 20s that are about 6 lbs heavier along w/ the wider tires that add a few pounds as well, I've not really noticed a significant mpg drop, I was getting about 29-30 mpg hwy bone stock and now get about 28. Ethanol will kill your mpg much more than some heavier wheels for sure. If you're planning to track your car often than weight would be a bigger concern, and if that's the case lighter 18s would be a good plan, especially if you don't lower it.
BTW, welcome to the site!

 

I would certainly like to know how do you get 28mpg highway or even better 29-30 stock... the best I ever got was loke 25mpg highway driving on the way back from Houston after I picked up my car... I guess that 7AT does wonders lol

 

I have a 2011 graphite shadow g37x sedan and currently get about 23 mpg with mixed driving. Really torn between matte graphite cv4s or cv5s. Of course coupe wheels or some lightweight mesh are still on the table. Going to drop it with some swift springs later this year. Thanks for the replies.

 

Mike, do you use pure gas or are all the stations using Ethanol? I get about 25mpg w/ Ethanol and 28 w/ 100% "real" gasoline. BTW, this is going 80 mph too

 

With an X you need to be extra careful w/ your tire diameters, it's usually considered acceptable to be within +/- 3% of your OEM diameter but several X owners have reported issues w/ their AWD at speeds over 80 mph. With a RWD the 3% seems OK but w/ the X you should be within 1%. Keep this in mind if you go plus size, for example w/ 19s you should run 245/40/19 on all corners or a 245/40/19 front 285/35/19 for best diameters or on 20s a 245/35/20 all around or 245/35/20 front 285/30/20
rear.Wheels in the 8.5-9"+35 to +40 front and 10-10.5"+45 rear will give you a nice flush fit when you drop it. Also if you plan on adding big brakes in the future be sure your new wheels will clear them prior to purchase, many wheels won't clear Akebono brake calipers.
Here's a good calculator to mess around w/ different setups


https://www.myg37.com/forums/tire_rim_calculator.php

 

Will 19 inch coupe wheels clear sport brakes?

 

The coupe 19"s are standard on BBK equipped coupes so they will clear the sedan BBK as well (since it's the same calipers on both).