It is entirely possible that the Tarquins appealed to Lars Porsena of Clusium (Clevsin), because he was the head of the Etrurian commomwealth for that year.
The Via Amerina was a road that broke off from the Via Cassia near Baccanae, and held north through Falerii, Tuder, and Perusia, rejoining the Via Cassia at Clusium.