Sir John, who died last year at the age of 97, was involved in local government for 60 years and spent 33 years as mayor of Port Chalmers.
Cr Andrew Noone told a council meeting this week the proposal was to name State Highway 88, from District Rd, Roseneath, to Wickliffe Tce, Port Chalmers, after Sir John. The 4km to 5km stretch of highway would be known as Sir John Thorn Memorial Dr.
The move was initiated last November by Port Chalmers man Les Box. He told the Port Chalmers Community Board that Sir John's family supported the idea.
Cr Noone said it was appropriate for the road to be renamed. It had been part of the Port Chalmers borough before amalgamation and Sir John had served on the National Roads Board as deputy chairman.