I don't get why anyone would want second hand tyres? To me that is like buying a second hand condom, I don't care seller is an ugly virgin who swears blind they only opened the wrapper to check it for size, it is not going to happen!
I can understand wanting to save some money, but when you are talking about less then £100 over 6,000 miles, which is the difference between brand new top of the range T30's @ £234 delivered and a special on a discontinued tyre that wasn't that bad in its day but was never top of the class, it hardly seems worth the bother. The actual saving is about the price of a pint of beer for every tank full of petrol (£3 every 180 miles). If that really was important, you would save a lot more by using some Contenental touring tyres that not only last 10,000 miles plus, but feel so shite that you never ride them hard enough to wear them out.