We all know that the motorcycle’s powertrain makes the wheels go round. Even so, we often fail to consider that it’s the tires that put the power to the pavement. But when a motorcycle’s rear tire suddenly and totally deflates for a variety of reasons, the ride goes flat. It’s that simple, and as mentioned in the Suzuki TR-750 sidebar, a deflated rear tire can pose catastrophic results, especially on a high-speed racetrack such as Daytona Motor Speedway.
As pointed out in that same sidebar, by 1975 motorcycle tire technology was improving quicker than ever before. For many decades prior to this movement, tire companies such as Goodyear, Dunlop and Firestone had served the market well, but for the most part, major advancements in technology were slow in coming.
Perhaps the most technological advances were found in road racing, and by the mid-1970s, following the lead set by the automobile road racing community, motorcycle tires with a slick, treadless contact surface began showing up at race tracks. Most notably, Dunlop and Goodyear assumed the lead roles in promoting this new breed of road racing tires.
Perhaps what ramped up development of motorcycle road racing slicks most quickly occurred shortly before the 1975 Daytona 200. Goodyear Tires and Yamaha spent several days testing multiple combinations of tires, using the then-new Yamaha TZ-750 ridden by Kenny Roberts. Kenny’s mission was to tell engineers which rubber compounds worked best, at least for the Daytona 200’s extreme conditions.
Gary Bryson, who served as the link between Goodyear’s motorcycle racing tire program and the motorcycle race teams, told the editors of Cycle magazine shortly before Daytona’s 1975 Speed Week about their private testing. As Bryson pointed out to the editors, “He [team rider Kenny Roberts] was just incredible during the testing.” Bryson continued, “After we had experimented for days and days with different chassis combinations and had used up 48 tires, Kenny said, ‘OK. I think I’ve got it.'”
Bryson further explained how KR then recited a litany of combinations that Yamaha and Goodyear could use during their Speed Week practice and qualifying for the 200-mile, and then in the 200-mile race itself. Of course, the final decision of tire compound could often be swayed by any immediate changes in weather conditions and track conditions, and so on prior to the big race.
Eventually, KR qualified with a new track record of 204.44 seconds/111.089 mph. In the early part of the race, he “opened up a paralyzing lead,” reported Cycle magazine, but by lap 9, his bike’s clutch “began giving up the ghost,” until he finally pulled in to DNF.
In the end, it was KR’s teammate, Gene Romero, who cruised to the win. The former AMA Grand National Champion won, not because he was faster than Roberts, but because he was tactful and careful not to abuse his bike, relying on that old saying, “It’s not how you start, but how you finish that counts.” Romero didn’t stress his TZ-750, or its tires in any way, allowing him to cruise to finish the race, and in first place.
