Just got back from an 800 mile round trip in my c220d and have a tale of woe to tell . Got a puncture at high speed on the M6 just outside Stafford called the AA to help and the man arrived promptly he removed the wheel (alloy) and put the spare on (steel wheel) i gave him the studs that were with the spare and he fitted the wheel . It was at this point that the wheels came off the trolly you see the studs that came with the spare were too long and when fitted they locked up against the rear disc .the AA man then called for a relay truck and i had to be taken with my passengers to Stafford to have a new tyre fitted to my puntured alloy expensive . Trawling through a scrappie in Gloucester i found a poor c180 that was written off i opened the boot and found it had a brand new steel wheel and five studs to match it they cost me a fiver and peace of mind for the journey home. The moral of this story is if you have alloys and a steel wheel spare then check it will actually fits the car and the studs will secure it to the car before setting out on a long motorway journey .