May be there is something already here but I haven't found it. I recently changed tyres on my Floride S because they had reached 10 years. They have had very little use. My understanding is that it is recommended by manufacturers that tyres should be changed every 6 years. But general consensus seems to be every 10 years. The reason given is that the tyres will have become hard by the heating and cooling cycles. The Qld Govt has no ruling regarding tyre change times. Recently did some hardness tests on new, used and very old tyres. The very old Michelins were not as hard as other brands of new and and used tyres. So my question is, if hardness is the problem why aren't use by times based on a hardness measure not age? Interestingly one tyre manufacturer claims their tyres do not go hard over 10 years despite number of heating cooling cycles. One for you Peter.