Motorcycle Safety & Driveability: Tire Cracks, catastrophic failure, quality problems

Question
I have a 1978 Kawasaki KZ1000A.  The tires on the front and rear still have a fair amount of tread left on them, but my concern is that they both have several cracks on the side of the tires.  Somebody mentioned that the chance of a tire blowing out because of cracks in the side wall is slim, but I wanted to check how much of a hazard it is?

Thanks
Stacey

Answer
Stacey,

If the tires have cracks in the sidewalls it's time to replace them, regardless of how much tread is left.

Tires deteriorate over time. Oxygen, heat, ultraviolet light, and other factors cause them to harden as they get older. When they harden they crack and discolor (blue). A harder tire does not conform as well to the ground and can cause handling and traction problems, as well as ride-quality problems.

A tire that's so old that it begins to crack has lost its useful grip life--the rubber is no longer soft enough to perform properly, which could put you at risk in a hard cornering or braking situation.

I don't know if an old tire is more prone to blowouts. Tires rely heavily on temperature to do their job. A hard tire will flex less, therefore heat up less, making it less likely to blow, but there could be other factors that increase its likelihood of catastrophic failure.

Pat