|Bring it on|
I had promised an update about tire sizes and different wheel fitment, so I'll get into that now. First off, I am NOT in favor tire fitment solely for the purpose of appearance. You might see this called "stance" or "stretch & poke" or other terms that basically imply pushing the wheels and tires out to as far (or farther) as they can go for the sake of looks. What I am in favor of is larger tires for higher levels of grip. More grip gives higher cornering speeds, better braking, and better control in all kinds of transitional maneuvers -- planned or otherwise. I'm definitely not in favor of getting the tire to a point where it will damage the body (or worse) at full suspension compression. If you can't use the car for its original purpose, what's the point of the whole exercise?
|17x9" Mach V Awesome with 255/40R17|
As I mentioned above, we've been running a 255/40R17 tire on a 17x9" +42 Mach V Awesome wheel at all four corners. We also run Whiteline Com-C upper strut mounts, which give us extra camber by moving the entire top of the strut, rather than by moving the tire/wheel relative to the knuckle, lke eccentric bolts would do. I mention this because a lot of BRZ/FR-S guys seem to run the eccentric bolts (or "crash bolts") to gain front camber, and this can lead to clearance problems as a wide wheel and tire can start to run into the spring perch on the OEM shock.
|18x9.5" Mach V Wicked Awesome with 265/35R18|
I could have put a 255/35R18 or 245/35R18 tire on the front 18x9.5" wheel, but those tire sizes would not be as wide as the wheel, and I'm really a big fan of having the right size tire for the wheel, and vice versa. But if you DID want to run the 18x9.5" Wicked Awesome wheel on all four corners of your BRZ or FR-S, I'd probably do a 265/35R18 in back, and a 245/35R18 in front.
|17" Awesome in front, 18" Wicked Awesome in back|
Plenty of people run different tire widths on these cars front-to-back, but I haven't seen anyone else do two different wheel diameters.
One final question the fans asked me to address is gas mileage after installation of the Innovate supercharger kit. On my daily commute, which is mixed driving, with a good amount of stop-and-go, I used to get as much as 28.5 mpg pre-supercharger. Since the supercharger install, I have seen 26.5 mpg when I stayed out of boost as much as possible. If I drive like a hooligan and flat-foot it every time I leave a stop light, I see more like 20 mpg. (Of course, when I drove like a nut before the supercharger I would take a pretty big MPG hit, too.) So basically, figure a 2 mpg penalty from the supercharger install -- a small price to pay for a 37% increase in horsepower!
Links: Mach V Awesome wheels, Mach V Wicked Awesome wheels, Innovate supercharger.