This is a photocopy from a 1:50,000 scale Survey of India map, and it shows clearly that Som la (present day Khardung la) is about 5370 m (17613ft) high.
Khardung la (actually Som la) in October 1973
The Nubra side of Khardung la (Som La) in October, 1975. That tormentiung glacier has melted away with today's traffic!
Khardung la (Som la) in October, 1977.
It is only 17,580ft in height. Or 5360 mtrs.
The Cartographic Institute of Catalonia, Spainm after several professional readings in 2005 gave the height of Khardung la as 5359.3 mtrs. The Indian Surveyof India map puts it at 5440m or 17843.2 ft.
With this lowering of height I hope that the hideous boastful sign boards will disappear too.
The highest motorable road in the world is now perhaps over Semo la in Tibet, China. Semo's height is 5565 m or 18,253 ft. Please see this link http://www.viewfinderpanoramas.org/ICCSemoKhardung.pdf