I bought the Z with R/F all round. Backs were replaced with non R/F Avons. I checked the rears and have 1.5mm over the tread blocks and done 11k since fitted. I am projecting / expecting 15k max. Does this sound about right? With all the threads on other brands I cannot find figures, has anyone had better miles on the rears. Pleased with grip etc and not driven hard to give premature wear. Fronts are still R/F with guesstamating about 24k from when they were fitted by the previous owner Any ideas greatly received.