The present invention is directed to a method of processing a rubber composition, comprising the steps of mixing at least one diene base elastomer with at least one additive selected from the group consisting of fillers, to a final temperature of about 150 to about 160° C. in a first non-productive mix step to form a first non-productive mix; cooling the first non-productive mix to a temperature of about 60 to about 90° C.; mixing the first non-productive mix with 0.1 to 10 parts by weight, per 100 parts by weight of elastomer, of a treated short aramid fiber having a length ranging from 1 to 10 mm and having a thickness ranging from 5 to 15 microns and comprising 3 to 40 percent by weight of a peroxide radical initiator in a second non-productive mix step to a final temperature of about 150 to about 160° C. to form a second non-productive mix; and mixing the second non-productive mix with curatives in a productive mix step to form a productive mix.