I've been searching for the same type of info for 7" wide rims. I would like to keep my '05 OEM rims but want stickier tires. I really like Michelin Pilot Sport PS2 tires and would like to mount these sizes:
Front: 235/40ZR17, rim widths: 8.0-9.5, 24.4 O.D. (+0.6 taller than OEM)
Rear: 275/40ZR17, rim widths: 9.0-11.0 25.6 O.D. (+0.7 taller than OEM)
Using the formula posted above: 7" x 25.4 x 1.1 and/or 1.3 = 195 to 231.1, the 235/40ZR17 size is outside the range. But has anyone run 235/40ZR17 before on 7" rims without any issues or concerns?