There are hardly more mutually beneficial relationships than ties between radio stations and events.Events have long relied on radio stations to drive ticket sales and extend sponsor reach, while radio stations have relied on events to access tickets, on-site booths and other inventory that can be used to create marketing packages that extend an advertiser’s reach beyond a 30-second spot.  But that paradigm is beginning to change.In a major shift in strategy, two of the largest U.S. r...