@elidie93 I have the same setup as you do and I play on 1080p (Playing on my TV; plan to upgrade to 4K in a couple of years) with max settings on everything, except longer shadows (for some reason, my game always crashes when I try to turn that on), turned off TXAA, MXAA only at 4x
Without mods, I'm running 100+ FPS avg, 88 in dense city areas, and around 50 in grass areas (grass is at ultra). I steer clear of 4K textures because I won't get anything out of it. Tried it once for the trees around LA along with other graphics mods, texture mods, and HQ car mods, and THAT finally bogged down my system to the point of crashing a few times here and there.
Once I get my 4K TV in a couple of years, I plan to get one of the best GPUs that will be around at that time. And with the 1080ti more than enough for 4K these days, I'm looking forward to what I can with whatever GPU comes out in 2 years