Method for producing a deflation-proof pneumatic tire and tire filling composition having high resilience

A pneumatic tire filling composition for producing a deflation-proof tire comprising a catalytically cured mixture of:

• (a) from about 3 to about 15 parts by weight of a polyisocyanate comprising polymeric diphenylmethane diisocyanate alone or blended with diphenylmethane diisocyanate or a modified diphenylmethane diisocyanate, wherein said polyisocyanate has an average functionality of greater than 2.3;
• (b) from about 20 to 65 parts by weight of a plasticizing extender oil, said extender oil having a %H below 10.00;
• (c) no added polyamine;
• and
• (d) an amount to bring the amount of the cured mixture to 100 parts by weight of a high molecular weight polyol or blend of polyols having a hydroxyl number in the range of about 20 to about 31 and having an actual functionality of greater than 2.1,
• the cured filling composition having a vertical rebound of greater than about 70% based on ASTM D2632, a Durometer hardness in the range of about 10 to 60 (Shore A), and a maximum temperature of no greater than 240° F. after 47 hours of the Federal Motor Vehicle Safety Standard #119 Durability Test.