I have a 2006 BMW X3 with 76,000 miles on the clock bought last year secondhand from a small local dealer. A few weeks ago the car developed a 'knocking noise' when slowing down to stop and then moving off again, eg when in heavy stop/start traffic. After a series of 'red herrings' my local independent BMW specialist diagnosed a Dual Mass Flywheel and clutch problem. They found that the flywheel had broken apart. They replaced the flywheel and clutch, costing me £867.68p. Less than two weeks then elapsed before a very similar 'knocking noise' occurred in the same driving circumstances.

I visited the garage today to be told that this time it was not a flywheel/clutch problem but another part of the transmission system and they were not sure which. More worryingly, this whole transmission saga, I am being told, could be caused by the fact the car is not fitted with BMW approved Pirelli or Michelin tyres. The garage’s next step is to fit the car with Michelin-tyred wheels to see if this solves the problem. Failing that it my need expensive transmission repairs to get it into a saleable state. I would be grateful for your comments on the view that the BMW X3's transmission system is so sensitive that it will not tolerate tyres other than Pirelli or Michelin. The garage says that many X3 problems are caused by the 'wrong' tyres.