I have a 97 528i (in the uk).On the front are 9inch 17s while on the rear I have 10 inch 17s.The car is standard ie has not been lowered and is not a sport model.The present set up is 235/45 on the front and 255/40 on the rear.The car handles well and I have no complaints except that I now need to change the tires.I am wondering if it would be a good idea to go 245/40 all the way round.If not what should I do? Please help.