On Mercedes 250 CGi Estate, rears (245, 40, 17 W) are being replaced at 21,000. Fronts (225, 40, 17, W) have many more miles in them. First experience of Continentals; good all-round tires that feel safe in all conditions. No hesitation in using Contis again (although I gather the o/e Sport3 has been discontinued and will need to replace with pretty much identical Sport5). Worth shopping around ... prices vary considerably.