This article is about the original A392 from Truro to Redruth in Cornwall. For the current A392 that runs to Newquay, see A392.
The now-unclassified former A392 in Greenbottom
The A392 was the original number of the road heading west from Truro.
Starting on the A39 just south of Truro Cathedral, the road headed west along Boscawen Street and out of town past the station. Continuing west, the road went through Threemilestone and Chacewater before ending on the A30 at Scorrier, a few miles to the east of Redruth.
In 1935, the entire road was renumbered as an extension of the A390, while the A392 number was reused for the former B3279 further north in Cornwall.
Later still, the western half of the ex-A392 was declassified when the A390 was rerouted along part of the B3277 (former B3285) west of Threemilestone, to reach the A30 further north.
A small section of the Western End of the ex-A932 now makes up the B3298.