I have a 05 Ford Mondeo TDCI. I have fitted some 18-inch ST Focus alloy wheels to it and on the rear I needed to add some 6mm spacers whilst doing nothing to the front. Due to adding the spacers the wheel nuts are only just connecting and as such are coming lose a lot, and one has now come off. I need the threads at the back extending by 6-7mm minimum to compensate for the spacers. I am looking for a reputable garage to do this for me as the Ford main dealer says they won't do it.