Keep in mind that running textures at max res can be really intensive on medium or low end graphic cards (650 Ti is medium range, starting level for gaming) since they won't always have the required graphic memory to store them.
Just as an example, going from a generic high to ultra setting might up your textures from 1024x1024 on average to twice more (2048), which will eat up 4 times more graphic memory.
The GPU power is another matter that will mostly play on the ability to display everything, from resource intensive rendering to post treatment.
The CPU itself, while often secondary, when too old or low end, can cause issues too, especially when it comes to physical engines, pathfind, and especially AI calculations, roughly.
Of course though, as you say there is always the bug possibility, especially with Bethesda...
EDIT : Are some random of your textures flickering like crazy between low res / high res? It's often indicative to graphic memory overload. Also on your screenshot, the tires are clearly low res. The people on reddit that speak about mipmapping clearly don't know what mipmapping is for (it prevents the textures to get blurry when seen at a very low angle, especially important for ground textures most of the time).