Part worn tyres,would you use them??

[markbubble]

iv used  x track tyres for years on my bikes with no problems at all but i do know where im getting them from (ie a friend and there free!) i personaly wouldnt mix tyres but i know lots who do with no probs ,just be certain thet the tyre is in great condition with no damage and as already said check for the date as you dont want them to be to old