I need a little help. I have a friend who bought a set of Helo 832 17x7.5Aluminum rims for her son's 1999 C230. While driving down the road a rim came off the vehicle and he almost crashed. My friend sent me the lugs to look at and test forgrade of steel and strengthbut I am almost convienced that who ever put the rims on used an impact wrench and not a torque wrench. The lug studs were supplied by West Coast Wheels Part # W27015CB Conical Stud Bolt 12 mm/1.5 RH/Tx 27mm. Does anyone know if these are the right studs for the Helo rim and has anyone had any similar experiences. Thanks

 

Wow. Scary. If all the studs broke and the wheel came off the car while driving it, then obviously something damaged the studs
and they failed. It's unusual if the correct lug nuts were used on the studs. The lug nuts HAVE TO be the correct ones for the WHEELS
you are using, and the right thread for the studs. Also the correct torque helps, but I doubt if a bit more torque on the studs using
the correct lug nuts would break every stud or said a different way, would cause EVERY stud to fail. I've seen them snap off using
an impact that can generate a tremendous amount of torque, but I think something else was in play here. Something did not match
something else......

 

as to your suspicions that someone used an air impact instead of torque wrench to tighten lugs, I would reckon that the vast, vast majority of shops do exactly that. one reason I generally try to do my own work on my cars. I have gotten cars back from shops a number of times where lugs were torqued way, way too high (probably twice what they need to be).

 

Could of been the wrong length of lug bolt, or maybe the bolt wasnt tapered to sit flush and tight against the wheel. This happend to a customer of ours who used after market lug bolts with his factoryspare. This was on a 211 though not a 203but same principle.Did the wheel wobble at all before it broke, or was there no warning?