The calculated distance (air line) between Ma‘arratmişrīn and Tadmur is approximately 135 miles respectively 218 kilometers.
By car or train, the actual journey to Tadmur is certainly longer, as only the direct route (as the crow flies) between Ma‘arratmişrīn and Tadmur has been calculated here.
Air line (approximately)
218 kilometers
117 nautical miles