Rubber composition with organic salt curing agent

A cured rubber composition that is based upon a cross-linkable rubber composition, the cross-linkable rubber composition comprising, per 100 parts by weight of rubber:

• a highly unsaturated diene rubber;
• between 20 phr and 150 phr of a filler;
• a sulfur vulcanization system of between 0.5 phr and 8 phr of sulfur and at least one vulcanization accelerator, the sulfur vulcanization system having a sulfur to accelerator ratio;
• and
• between 1 phr and 6 phr of a metal salt of a carboxylic acid that increases a tear index of the cured elastomer composition by at least 50 percent as compared to a similar cured elastomer composition, wherein the similar cured elastomer composition is different in composition only in that the similar cured elastomer composition (1) lacks the metal salt of a carboxylic acid and (2) has an increased amount of the sulfur vulcanization system at about the same sulfur to accelerator ratio, the amount increased to maintain a 10% modulus of elongation at 23° C. to within 15% of the modulus of the cured rubber composition.