I always fit washers on the outside of the dropouts, and also on the inside when space allows, to give a bit of extra clearance to the hubs and tires to the chainstays. Same with my forks. The number of washers each side depends on the hub/freewheel set up and freewheel/chainring/chain alignment. The back end on my gjs freestyler is tighter than cher lloyds arse, so no room for washers on the inside. I'll probably never ride it though, so it doesn't really matter