Since Nokian did the right thing further speculation may be pointless. I have seen this in the past. Possibilities besides a defect include chemical contamination  such as brake fluid or more likely the van parked with water underneath as in a puddle and the water froze. 

Dennis
 

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Michael Hart
Sent: Saturday, November 22, 2014 11:20 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Nokian Tire Sidewall Cracks (photo)

http://s1288.photobucket.com/user/mjhart853/library/

Michael Hart
Palo Alto, CA
'87 2WD Westfalia ('T3WESTY')