Phil,
You are dead on with your calculations of a offset of 38 mm. I have no idea where the 49.5 mm offset figure is coming from, but it is the number I have heard for some time now. The only other piece of information I have is that the ST200 wheels sold by BAT (17 x 7), supposedly have an offset of 38 mm, which would now make more sense if the stock SVT wheels have an offset of 38 and not 49.5. Like you, I want to get to the bottom of this before I purchase new wheels.
Andy
