Tyres don't really worry me, as I am not hard on tyres, nor am I particularly worried about the longevity of a diesel engine. I know you get occasional major failures (my son-in-law had a crankshaft snap in his works Discovery. He couldn't believe it, and it cost his company several thousand pounds to put right), but in my experience, petrol engines fail more often than diesels. But all this looks immaterial, as my wife is adamant that she doesn't want us to buy a diesel (she doesn't even drive), and explaining to her that if I don't buy it someone else will isn't cutting much ice!