That's what some people are saying in other threads. I'm about to go through my cars and make sure their skins aren't 4k and if they are then dumb them down to 2k. From there I'll probably remove some vehicles so there's not too many different types driving around.
Update: So I changed all my skins to 2048 x 2048 and adjusted my in-game textures down by one. I played for a while and so far I haven't seen any texture loss like I was seeing earlier, even with a lot of officers and vehicles around.