Tire sizing tolerance

[one_bad_rover]

Hey all. Great space here. Ive had bimmers for quite a while but we finally pulled the trigger on a little 4.6is. The truck was 8K and we are into it for another 10k in repairs (stem guides, timing chain fun, the list goes on) But its at 100% currently.
Heres the dilemma, its an early 03. I bumped tire sizing pretty significantly, putting some 285/50/20s on the back and 265/50 20s on the front, my variance in revolutions per mile is 17. (646/663)
Everything seems fine, no crazy noises or lights, but after reading around here. Im a bit concerned. I dont see alot of people running larger tires, nor working these little guys much. This is a sport mobile for my wife. Its purpose is to get her bikes and paddleboards where they need to be.
Hence the beefier, more aggressive tires, she will be very light off-road but off road nonetheless.
Input, suggestions or things to keep an eye for? Thanks in advance!