Patent ID: 7389802

Claim:
A pneumatic tire comprising a carcass and an innerliner bonded to an inner face of the carcass, said innerliner comprising a double layer structure including a first innerliner layer of non-foamed rubber adjacent the carcass and a second innerliner layer of in situ-foamed porous rubber forming an innermost surface of the tire with a chemical bond between the first and second innerliner layers, wherein the first innerliner layer is cured from a green composition and the second innerliner layer of in situ-foamed porous rubber is cured from a green composition comprising a nitrogen-releasing foaming agent that decomposes upon curing of the tire in a mold to release nitrogen gas, wherein the chemical bond is formed between the first and second innerliner layers upon co-curing of their respective green compositions, and wherein the second innerliner layer has a post-cure physically altered innermost surface having a plurality of open cavities physically formed therein after curing the tire in the mold by one of knife cutting alteration or a laser perforation alteration, and wherein the plurality of open cavities have a mean diameter of about 50-250 μm.