So had a flat tire recently and called MB roadside. It was a long weekend and all of the local shops were closed already. I didn't want to tow the car and leave it parked for 2 or 3 days. The tow guy offered to help me replace the flat with the spare. When he tried loosening the lugs, simply couldn't do it! They were way too tight. I have to say the tow driver put his full back into it and the lugs just wouldn't budge. Finally when I thought the lug had come lose, the lug head (cap) had actually come off the lug bolt. Since I bought this ride used last year, I haven't had to remove the tires and no idea when the previous owner did either.

Now I am worrying about over tightened lug bolts and what kind of damage they've caused. What's the worst case scenario from over torqued lug bolts?

Also, I'm looking to replace the typical MB lug bolts that come with a cap to the ones that don't have a cap so I never have this problem again i.e. cap coming off the lug bolt. Does anybody know if MB makes original lugs without the caps? Or am I gonna have to go third party? If so, any good suggestions in terms of a third party lugs?

Finally, I haven't even been able to confirm the size of the lug bolts on this particular model. Its nowhere in the manual. Does anybody know the size or the part number that I should be looking for?

 

Do you have evidence that the bolts were over tightened? Nothing I read in your post suggests this. Over tightened bolts mean stripped threads in the wheel hub. You didn't mention this. Have you affirmatively verified that the hub thread(s) is (are) stripped?

Absent stripped hub threads, you are fine.

The cap coming off a lug bolt is not a problem in the long run. The cap is cosmetic. Order a new lug bolt from your dealer, install it and forget about it.

If you want a third party option, Google will be your friend with this. Also have a look on mercedesbenzstarparts.com. Please report your research findings.

 

Sounds like nut was cross threaded or someone used the air gun instead of a torque wrench.

 

Considering you're in Canada, I'd suspect that the bolts got rusty. I'd have them all checked and make sure they use anti-seize compound on the threads. Any that have rust should be replaced.

 

I hate the lugs on this car. The head seems shallow and they're also exposed, which gets them caked with grime. The result is they're hard to break free and the wrench slips easily. I've rounded bolts the first two times I tried to remove a wheel.
First time was trying to change a flat. It totally sucked because I was almost an hour from home with one of my children. One bolt was crazy stuck and I rounded it, so suddenly we're in need of a flat bed.
Second time was at home where again like the wrench my breaker bar started slipping and rounded a bolt. I solved it by upgrading to a nicer, longer, 1/2" breaker bar.
Never had this problem with any other car.

 

Thank you all for your input. I've learned a lot about lug bolts over the last couple of days.

Turns out my initial worry, which was the cap coming off the lug bolts wasn't really a worry. All I had to do was move down a socket size from 17 to 16. I'm including a couple of pictures of what I thought was a problem but turned out be not a big problem.

Having said that, I've got much bigger headaches now with a broken lock-nut key and broken lock nut. I'm going to start a new thread and hope for some ideas on how to deal with that situation.

Lug bolt with missing cap at 4 O'clock position

Lug bolt cap with rounded corners

 

First thing I suggest that you do is replace all 20 lug bolts on this vehicle. They need it. They are beat up, rusty, and apparently a few are broken/stripped.

A tire shop will get you sorted. They deal with broken and damaged lug bolts, lug nuts and wheel locks every day. Go to a high volume tire shop in your area (Canadian Tire?). Toronto should have alot of them.

 

This tool will address all these issues and will prevent ANY further damage to benz weird shape lug nuts.... without this tool, lug nuts will get destroyed by the standard 17MM wrench that shops have.... just hand it to them and let them use this tool and ONLY this tool on the OEM lug nuts.

 

Never use anti seize on wheel bolts or lug nuts. It decreases friction allowing more bolt tension to be achieved for the same torque. More bolt tension risks bolt fatigue and failure at the worst possible time.

A solution for a ruined lug nut or bolt is to hammer a socket onto the lug nut/bolt. Choose a socket size just large enough to be smashed over the lug nut/bolt. An air impact will finish the job. The socket is sacrificial and will be ruined in the process but you will have removed the lug nut/bolt.