525i with 20's...? doable? realistic?

I have a 2004 525i and I'm considering putting 20" replica 166 wheels on it. They come with tires for $1000, and they are slightly used. I am buying them from a buddy. The car is riding on stock suspension. I am also considering coilovers to slightly modify the ride height and stance.

Tire size:
245/35/20
275/30/20


Does anyone have any input to add? Is the 20 a bad idea on this car? Has anyone done it and been satisfied?

I also come from a past of lowering all my cars, with big rims and low pro tires so I do understand the concept of it, but just unsure if this is the right decision.

Any help would be great!

and my username is 10til6FAVEe60 because I wrecked my 2006 550i which had OEM 166 19' wheels and I loved the sh*t out of that car.

Thanks!