Most tyre dressings are just that, a surface dressing that bonds to a clean surface to maintain a clean black 'look' to the tyres surface.
Tyres are manufactured from a composite of rubber and highly cross-linked polymers to increase durability, flexibility, toughness and prevent air loss along with compounds such as rubber with reinforcing materials such as fabric and wire, natural rubber or Polyisoprene is the basic elastomeric polymer used in tyre making.
'Hydration' is provided by the antiozonants and waxes that are formulated into the polymer composite.
Antiozonants, along with carbon black, the tyre manufacturer mixes in antiozonant and other protective ingredients to repel ozone from the rubber. These waxes and polymers migrate through the tyre at a molecular level to form a barrier against harmful ozone.
As the tyres move (with the car being driven) the rubber flexes and heats up, allowing tiny amounts of the wax to surface. When a vehicle is not being driven (i.e. classic show cars, winter storage, etc) then without this action and the rubber can easily dry out and rot.
