I went over and looked at the local "barn find" '30 coupe that's been sitting since at least 1946 that we know of. No telling if it's 1930 factory stock.
The wires run down the frame, clipped in 3 places. Last clip is about a foot from rear of body on frame rail.
Then there is about 2 inches of wire to bullet connectors to tail light harness which is run through old fabric type wire loom tube, looped under fender mount brace (touches but no clamp/support etc) to tail light.
I suppose tire could get in the way, doesn't look like it has. Still works.