I'm very happy with the standard "big" wheels on my 3.0i e53 that are 255/55/18. (square).
Wifes e70 with 50i and 450 ft·lb. Uses the same right now and it's nice for comfort not so good for tire wear.
https://tiresize.com/calculator/
I'm planning to get 275/55/18
(Square).
3.1% bigger so 72*1.031=74.232 means at 75 on dash actually going 74.2 vs. 72 bringing speedometer closer to reality.
Also 9% more sidewall for more cushion.
Same size might work very well for you. Exactly same circumference so no change in speedo buy 9.1% bump in sidewall