I had a set of 4 tyres with 90% tread on them on a caravan I bought that lasted 800k's before 2 of them blew out and wreaked a mudguard and spat on the van in the process.
When I took the van in for a new set of tyres I was told the the ones on the van were 9 years old, So regardless of how good the tyres look age DOES matter.

