One of the most significant enemies of half-track tracks is moisture.....much like rebar in concrete.
Once a crack in the rubber reaches the steel cable that form the core of the track, the cables begin to rust....the growing rust forces the rubber away from the track, widening the crack, letting more moisture in, and the cycle continues.
Soooo........this can't be stopped, but you may slow it by avoiding getting the track wet, and some folks advocate sealing the cracks with a rubber compound (similar to recommendation above) in order to inhibit further moisture intrusion.
Best wishes,
David Doyle