Tire dry rot refers to the cracking and splitting that can occur in the sidewalls or treads of rubber tires as the rubber ages and becomes brittle. It is also known as sidewall cracking. Ozone and ultraviolet light are the primary environmental causes of tire dry rot. Tire manufacturers blend chemical ingredients into the tire during the manufacturing process in an effort to combat dry rot caused by ozone and UV exposure. Carbon black is added to the rubber to protect the tires from UV light. Waxes are added to the rubber during tire manufacturing to protect the tire against damage from ozone. If the vehicle is left to sit, the tires may develop dry rot. Make sure to check the tires regularly for any issues they might have.