275x40R20 overall diameter: 28.66inches or 728mm

285x35R20 overall diameter: 27.85inches or 708mm diameter change by -20mm
285x40R20 overall diameter: 28.98inches or 736mm diameter change by +8mm
295x35R20 overall diameter: 28.13inches or 715mm diameter change by -13mm
295x40R20 overall diameter: 29.29inches or 744mm diameter change by +16mm

305x35R20 overall diameter: 28.41inches or 722mm diameter change by -6mm


In my opinion if somebody wants to change the 275s with wider tyres the best size is 305x35R20. With this size your RRS will be (only!) 6mm shorter. That will cause - i think - no problems at all...speedo, geometry of the car etc...
My question is: Will a tyre 305x35R20 fit on the OEM Wheel??? RRS TDV8 HSE Java Black

The recommended rim width range for a 305/35R20 tire is 10 to 12", the stockers are 9.5" wide... So you'd be pushing it a bit by fitting such a wide tire on the stock wheels. I also have the feeling you'd end up rubbing the inner front sidewall against the upper control arm, as there is already very little clearance between arm and tire with a stock setup.