Service intervals are 9000 miles or 1 year tyres can be done for under £400 for all four if you switch to Falken FK452. At a guess your running RE040 which are rubbish for UK weather conditions they require a lot heat in them for good performance and the Falkens are well liked in the UK get yourself over to 350Z-UK for more info.
I bet the Falkens are well liked because people have convinced themselves they are amazing as they are easy on the pocket, in reality there are countless better tyres, though as a car ages the better tyres lose favour with the owners club as new owners become more budget concious and will seemingly stop at nothing to convince themselves and others that the cheap option is just as good as the more established performance tyres. Can't remember the last time somebody said 'Continental' on some of the BMW forums
