I have also included my measurements:
FRONT
20mm - Front inside
5mm - Front outside
240mm - Guard to strut
160mm - Gaurd to lower coil seat
80mm - Lower coil seat to strut
180mm - Hub face to strut
105mm - Hub face to lower coil seat
55mm - Hub face to guard
605mm - Tyre height (when under vehicle load)
635mm - Lower coil seat height
30mm - Travel height
REAR
30mm - Rear inside
30mm - Rear outside
265mm - Guard to strut
265mm - Gaurd to lower coil seat
0mm - Lower coil seat to strut
190mm - Hub face to strut
190mm - Hub face to lower coil seat
75mm - Hub face to guard
605mm - Tyre height (when under vehicle load)
675mm - Lower coil seat height
70mm - Travel height
EDIT (Feb 1): The following measurements are based on my newly fitted RX8 wheels 18x8 +50 with 235/40/18 tyres.
FRONT
12mm - Front inside (was 20mm)
0mm - Front outside (was 5mm)
REAR
16mm - Rear inside (was 30mm)
13mm - Rear outside (was 30mm)
Current wheels: 16x6.5 +52.5, 205/55/16. The weird thing is that I measured the wheels from inside rim to outside rim/face and it was 192.5mm, which is ~7.5" (the rim width is supposed to be measured from the inside of the rim but this should make that much difference - maybe 10mm/0.5"?) But the wheel definitely has 16x6.5 OFFSET 52.5 stamped on it.