went to Khewra Salt Mines in start of May this year..
as soon as you get off M2, road is nonexistent .. they've unpaved all the road going through Pind Dadan Khan and Jhelum area... and car couldn't go above speed of 20-30 km max... and had to redo suspension work when i got back home
...
so unless you have a off roading machine , keep in mind the bumpy and trashy ride of around 2 - 3 hours when you get off the motorway : )
otherwise, salt mine itself was a pleasant site to visit 7/10 .. but road was 1/10 : (