misterzero1

A problem has come to my attention. It not only affects me, but potentially all Mercedes-Benz vehicles sold in the US. The result should be a recall for visual inspection by a dealer, and replacement, if necessary for all wheels affected - at least those under warranty.
It has come to my attention that Mercedes Benz uses cast aluminum wheels that contain a casting defect, and this is done knowingly.

This particular defect is called a “knit line”. When a wheel is molded the molten aluminum alloy splits into two paths, or fronts, and meet up on the opposite side of the mold. A knit line is where debris in the casting mold gets pushed ahead of the fronts and prevents these fronts from joining, or knitting, together. This causes a weak spot in the circumference of the wheel. It appears as a dark “V”. The danger comes from the fact that this reduces the cross sectional area of the outer rim of the wheel (For example: if the outer rim is normally one inch thick, the defect lessens that dimension to one half inch or less, right down to zero). As the wheel turns in service there is a repetitive load put on this defect which could cause it to grow and eventually split the wheel.

Of course Daimler-Benz is aware of this – warranty for wheels is only one year or 12,000 miles, and non transferable.

In summation:
Daimler-Benz knowingly puts defective, possibly hazardous, wheels on their vehicles. The failure rate within the one year warranty must be low, but they will fail given enough use.

I purchased a 2008 vehicle where all four wheels have this problem. One wheel has continued to crack all of the way through the outer rim of the wheel.

freewheelb

I think I have the same issue on my 2006 c230.

I was checking out the rear passenger tire after a flat and found a crack in the wheel that was leaking air. A smaller crack is forming on the opposite side too.

StarvingArtist

They all spring a gas leak too! I must be as crazy as people say, I've bought 3 and I'm thinking about an SL65.

misterzero1

Do the cracks initiate from a casting defect as I have described? How many miles are on the wheels? Can you upload a photo of these cracks to help me identify them?

misterzero1

Just as I suspected - one wheel has a crack in the area of the cast defect.
See attached picture.

misterzero1

MB has hidden their cracked wheel problem by shortening warranty on wheels.
MB's basic warranty is 4 yrs./50,000 miles, but wheel warranty is only 1 yr./ 12,000 miles.
For these manufacturer's, wheels are covered under the basic warranty: BMW, Audi, Toyota, Honda, Chevrolet, Buick, Cadillac, Ford, Chrysler, Hundai.

According NHTSA Complaints (I checked ) MB owners who bring their cracked rims in are told by the service mgr. that crack was due to impact - not covered under warranty.

I love my MB's, but I don't like it when a big corporation is getting away with hiding poor quality.

Please spread this info around.

misterzero1

The Federal Government States: “If a safety-related defect exists, the maker must fix it at no cost to you – even if your warranty has expired.” Quoted from the USA.gov Consumer Action Handbook.
Wheel cracks are safety related aren't they? So it's worth the effort. If you have cracked wheels and your dealer will not replace them or give you the price to replace them, then give them a look at this document. (It can be downloaded or ordered at “publications.USA.gov”.)
Further, if there is no sign of impact to the wheel, it has been determined that a defect has caused the crack (by fatigue as I have mentioned.)
Of course the wheels will have to be inspected by a MB Dealer. And don't expect help from them. Deal directly with MB. Contact them through their website.
Of course you don't want a replacement because it might have the same defect as the original. Ask for the price it would cost to replace them.
I will give more detail as I get the chance. In the meantime, good luck!