They major high poly objects I still see in the first edit is the ball in the middle and the roundish screws. just remove the top of the screw or make it only 4 poly / edged instead roundish.
You can make any model decent looking with low polys
For this especially just take Futo rims and try smoothin them out/re making them until they look almost exactly like Watanabes
That might be the best way if you can't scratch it