The B245 runs along the original route of the A21 into Tonbridge from the north. It gained its current number when the Tonbridge bypass was built in the 1970s.
The road starts at a roundabout GSJ on the A21 at the point where that road moves from the Sevenoaks bypass to the Tonbridge bypass.The ex-A21 north of here is now the A225 and there is a short link road for southbound traffic along the original line of the A21 bypassing the roundabout, which lies a short distance to the west.
The B245 heads southeastwards, initially parallel to the A21 but the roads diverge after about a mile. Presently the road enters Hildenborough which stretches along the road for some distance. There's then a very brief rural section before the outskirts of Tonbridge are reached. The road ends at a triangular junction on the A227 to the north of the town centre. The mainline of the B245 reaches traffic lights and is forced to turn right; traffic wanting to go the other way runs along a short spur which ends at a T-junction just to the north.