245/40x20 on the front and 275/35x20 on the rear with the stock wheels fit fine. No clearance issues. This set up also keeps the diameter almost exactly the same as original.
There are also many more tire choices in these sizes.
Going with the 265 will give you a smaller diameter tire than originally installed and more speedometer error.
All of these tire sizes including the 265’s are slightly wider than the tire manufacturers recommend installing on the narrow stock i8 wheels.
https://tiresize.com/comparison/