I don't have any feedback on the wheels, but be sure to check the diameter of the tires, I recently tried to fit a set of Hankook RS-3 in the following sizes: 245/40/18 and 285/35/18.
The 285/35/18 fit in the back, but the 245/40/18 were too tall and did not fit in the front because they contacted the lower spring perch on the strut.
Here is a comparison of sizes:
It looks like your front size is the stock 987 size. I have heard that it fits but I bet it is tight. My tire was .3" taller and did not fit and it was pressed on there pretty tight.
Stock 986 Boxster front - 205/50/17 - diameter 25.1" (from Miata.net tire size calculator)
Stock 987 Cayman front - 235/40-18 - diameter 25.4" (I have heard this fits on a 986 but it is tight)
This larger front size - 245/40-18 - diameter 25.7" (too tall for 986 fronts)
If it is stock 987 sizes it would probably fit, but there is nothing like the feeling of schlepping a set of wheels and tires around, and installing them and they don't fit
