Anyway four nuts distance apart crossways from the centre of each nut to its opposite nut is 5 and a half inches, and they are four inches from the next nut to the side.
The diameter of the wheel seems to be 14 inches. Happy to send a photo with a tape measure in the picture if it helps. Don't need new, any old functional wheel will do as its for the spare anyway. Also do you have caravan towing covers and I'm after a caravan hitch cover.