Tell me about tyre's!!

On the ride today I was saying about a ridge on the trailing edge of the tread pattern on my rear tyre and was told its due to acceleration out of bends. While showing this I mentioned that I was getting close to needing a new front tyre and that it was original from 2008 and has covered 30,000 kms (I have not included the 19,000 kms from the UK to here!!) which is quite impressive but is is the most distance covered on a tyre?

Also what make would you recommend for a cruiser?