WIDER TIRES & MILEAGE DROP??

OOPS! WRONG FORUM!! (then report the post and let us know. I happened to read the post so I moved it but next time report it to let us know and we'll move it)

I upgraded my Two model v's 16" rims to be identical in measurement to the Five model's wheels with lightweight 17" X 7" ENKIE RPF 1 wheels and Yokohama YK 580 215/50/17 tires.

Tire Rack tells me my 7" wide wheels are in the middle of recommended wheel width for 225 wide tires. I'm wondering if I get these wider tires for my next set of tires how much mileage I'll lose.


MY CURRENT HANDLING MODS:
1. Tanabe lowering springs
2. Cusco strut tower bar
3. Tanabe 2 point front crossbrace
4. Cusco front lower arm brace
5. Cusco center chassis brace
6. Tanabe front sway bar
(7. possible Cusco rear sway bar this spring)

So the chassis and suspension have now been sufficiently stiffened to take advantage of wider tires.
I'm sure the car will handle better with 10 cm. wider tires as wider tires usually provide the most noticeable improvement in handling of any single modification.

But will I lose at least 1 mpg? Anyone running 225 width tires?