The calculated distance (air line) between Khorramshahr and Ar Rumaythīyah is approximately 78 miles respectively 126 kilometers.
By car or train, the actual journey to Ar Rumaythīyah is certainly longer, as only the direct route (as the crow flies) between Khorramshahr and Ar Rumaythīyah has been calculated here.
Air line (approximately)
126 kilometers
68 nautical miles