Police are appealing for witnesses to the incident which happened near Witton-le-Wear at 8.30pm on Thursday (September 4) evening.
A spokesman for Durham Police said that the man, who lives locally, was riding a blue Suzuki south when he saw the tractor, towing a 32 ft-long trailer, pull out of Saunders Avenue onto the A68.
He took evasive action to avoid the tractor but his bike left the road.
He was taken to Darlington Memorial Hospital where he died from his injuries. The tractor driver was unhurt.
Police would like to speak to anybody who may have seen the motorcycle on the road at or around the time of the collision.
Anyone who can help should contact Durham Police on 101 of the force’s collision investigation unit on 0191-3752159.
