The composition of the intermediate for steel adhesion is dependent on the compound formulation. A higher sulfur content is necessary for adhesion than for ordinary rubber. Since oxidation of the high sulfur rubber is one of the degradation pathways that can lead to tread separations and most of the oxygen responsible for rubber oxidation comes from the inside of the tire, one of the methods to reduce the oxidation of the steel coat skim is to apply an oxygen impermeability rubber as an innerliner.
Halobutyl rubber is the polymer chosen in the tire innerliner compound due to its excellent air impermeability, preventing oxidation at the steel belt compounds.
Use of 100% of halobutyl rubber in innerliner compound leads to increase tire durability.