is important to include a processing oil an extending oil in the rubber composition at a level which is within the range of about 20 phr to about 90 phr it is preferred for the processing oil to be present in an amount ranging from about 30 phr to about 70 phr it is most preferred for the processing oil to be present in the rubber composition at a level which is within the range of about 40 phr to about 50 phr zinc oxide is also included in the rubber composition at a level within the range of about 1 phr to about 10 phr it is normally preferred for zinc oxide to be present in the rubber composition in an amount which is within the range of about 3 phr to about 8 phr it is normally more preferred for the zinc oxide to be in the rubber composition at a level which is within the range of about 4 phr to about 6 phr stearic acid is also included in the rubber composition in an amount which is within the range of about 0 25 phr to about 5 phr it is preferred for the stearic acid to be present in the rubber composition in an amount which is within the range of about 0 5 phr to about 4 phr it is most preferred for the.