Larry Lawrence has posted a picture of me at the 1990 WERA GNF on his blog the Rider Files.
https://riderfiles.wordpress.com/2012/09/12/bsa-vs-harley-davidson-25-years-later/ As I commented, the bike is a BSA B-50 that belonged to my friend, the inimitable Dick Miles, and the legendary Dr. John Wittner had previously 'laid hands' on it.  I stated that it came with Dunlop K81 tires, which Jim Allen, Dunlop's race tire chief at the time, told me were at least 20 years old.  Upon reflection, that seems like it must be an exaggeration, as twenty years previous to 1990 was before the B-50 went on sale.  But, in any case they were old, and I learned that while they maybe hard, they're not unpredictable.  So, as with any tire, sneak up on them and find where the limit is.