Can someone explain what exactly the track texture setting changes? I tried 512 MB and 4 GB and I could not see a difference. Comparison screenshots would be nice to point out the differences.
I think it has nothing to do with quality but streaming. I think it's the manual selection for how many GiB of textures shall be loaded at once and the rest get streamed.
I think so, because nowadays many games work this way (F1 2015 does, too) loading as much textures as possible into the memory of the graphics and if it's not enough the rest gets streamed in and out.