The fire started on a small part of the trailer at about 6am on the westbound carriageway between Bayston Hill and Edgebold.
Three fire crews were sent to the scene from Shrewsbury, along with an operations officer. The crews left the scene at 6.42am.
A spokesperson for Shropshire Fire and Rescue said: "Three appliances were mobilised from Shrewsbury and they used crews used small gear to put the fire out.
"One hose was used to put the small fire out on its trailer axle."