Q: Why do new dirt bike tires get more grip than old dirt bike tires?

My research: I have found that new tires have more traction not only because they're
new but because more friction is created when accelerating or deaccelerating. More
traction will allow for more acceleration, speed and or velocity, when deaccelerating
or stopping more friction is applied to stop the bike which creates more inertia.
Momentum
of the bike is greatly reduced with new tires. Less friction is created when
old tires are being used, because of less friction on the surface. Certain types of tires
have been developed for different types of terrain to get the most traction. When going
up a hill requires more friction to push the bike up the hill or to go off a jump, when jumping
the force of gravity pressing down on the bike applying inertial pressure that the tire must
withstand. When the landing occurs more traction is needed to keep the bike stable enough
to finish the race.
new tire
new tire
old tires
old tires