newer merc wheels use 14mm...can these wheels be used on older(w126) cars, that need 12mm bolts. It seems to me the hub is keeping wheel concentric, and as long as the bolt type, cone or ball end, is right I should be ok. Can anyone advise? if need be can the 12mm bolt be sleeved to 14mm?

So long as the offset is correct you can use them just fine.

You do need to fit custom lug bolts that have the following dimensions: R14xM12x1.5x {proper shank length in mm}

Typically the proper length will match the length of the original lug bolt for the source vehicle. For example, if you were fitting W211 wheels to your car you could use either 26 or 28mm length.

You can get the custom lug bolts from radusadirect.com, they are usually around $70 with shipping for the complete set. There are not many suppliers of these things and I've found rad to be very knowledgeable and reliable, and the bolts are very high quality.

Good luck.

good answer

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Rick, I would be reluctant to use 12mm lug bolts on a wheel designed for 14mm lug bolts because I doubt the seating surface area on the 12mm bolt is identical. The correct torque for a 12mm lug bolt is 80ft/lbs while a 14mm lug bolt requires 100ft/lbs. You may want to discuss this subject with the Service Department Manager at your local MB dealer to avoid a compromised safety situation. If the manager doesn't know immediately it's likely he could get a recommendation from the MB engineering staff.

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Fred Hoelzle

That is exactly why I told him to use the custom lug bolts and gave him the source for them.

The custom lug bolts have a ball seat that MATCHES the ball seat in the newer wheel. That's the R14 part of the description.

The torque spec remains the same, 80 ft/lbs.

It is the same principle as fitting any aftermarket wheel.

Many people have done exactly the same thing and have had no problems whatsoever -- myself included.

CK, there's a reason MB uses 14mm lug bolts on the newer wheels instead of 12mm lug bolts ... the newer, larger wheels produce greater loading on the lug bolts. Custom lug bolts may provide the same ball seat surface area, but the 12mm lug bolts can't handle the same loads. Newer wheels require 100ft/lbs clamping force, not 80ft/lbs. A 12mm lug bolt reduces the margin of safety. I don't claim to know if the reduction will ever cause an accident, or make an accident worse; but I wouldn't take that risk.

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Fred Hoelzle

" there's a reason MB uses 14mm lug bolts on the newer wheels instead of 12mm lug bolts ... the newer, larger wheels produce greater loading on the lug bolts. "

Do the wheels produce greater loadings or is it because the newer car has more power / weighs more / has more cornering capability?


"Custom lug bolts may provide the same ball seat surface area, but the 12mm lug bolts can't handle the same loads. Newer wheels require 100ft/lbs clamping force, not 80ft/lbs. "

Do the newer wheels require higher clamping or is it the higher capacity of a 14 mm bolt the reason tq is higher?

As for sleeves, I'd tend to sleeve the 14 down to 12 so the shank of the bolt has someting to bear against. ( Yes I know the custom bolts will have a properly sized ball. )

97 SL320, the only large wheels I'm familiar with that use 14mm lug bolts are the 19" wheels on my son's BMW 745i. Those wheels/tires are significantly heavier than the wheels/tires on our 124 cars that use 12mm lug bolts. It only makes sense that the increased wheel/tire weight increases the dynamic loading on the lug bolts, therefore the lug bolts are larger diameter.

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Fred Hoelzle

Found this when researching wheels and offsets and so on.

Wheel Bolt Pattern Cross Reference Database and Conversion Guide: 5*X*114.3

With that said, what about the AMG lorinser or carlsson wheels made for the w124s. They were 17s and 18s and 8inch wide at least. Pretty sure they still used the same bolts among all w124s and weigh more or less the same (usually much more) than modern day wheels. So as long as the seat is okay and the torque is okay I don't see a problem. Correct me if I am assuming something incorrectly.