Help - Just purchased CPO'd 2013 GLK 4matic and discovered one tire is wrong size!
08-05-2015, 02:53 AM
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Help - Just purchased CPO'd 2013 GLK 4matic and discovered one tire is wrong size!
Just purchased a 2013 GLK 4matic CPO'd by my local dealer 4 days ago. Upon closer inspection I discovered the driver's side front tire is a 235/40 (20 inch wheels) compared to the other tires which are the correct size 235/45. Needless to say I am very concerned that this tire has been on the vehicle for some period of time - possibly 5k - 10k miles. The size difference circumference-wize is about 12.5% larger on the 235/45 compared to the odball 235/40. (.4 x 235 = 94, .45 x 235 = 105.75; 105.75/94 = 1.125 or 12.5%) My understanding is some of these cars have had transmission/transfer case issues under ideal circumstances.
1. Really concerned what damage this size difference may have already caused to the 4matic system - I have searched this topic however I have not been able find any definitive info (yes, I am well aware of the general awd rules of same circumference tires, etc.) as to what damage a huge (percentage-wize) size difference could potentially inflict on the 4matic system. There is no mention of any potential issues in the owner's manual either.
2. Based on this situation how should I proceed with the Dealer or MBUSA - I have already spoken to the service manager and he has agreed to relace the tire.
Any advice or input would be appreciated.
1. Really concerned what damage this size difference may have already caused to the 4matic system - I have searched this topic however I have not been able find any definitive info (yes, I am well aware of the general awd rules of same circumference tires, etc.) as to what damage a huge (percentage-wize) size difference could potentially inflict on the 4matic system. There is no mention of any potential issues in the owner's manual either.
2. Based on this situation how should I proceed with the Dealer or MBUSA - I have already spoken to the service manager and he has agreed to relace the tire.
Any advice or input would be appreciated.
08-05-2015, 07:54 AM
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2020 C8, 2020 defender 110X, 2019 720S, 2014 GLK 350 4matic, 2015 escalade platinum, 2013 RRS HSELux
Help - Just purchased CPO'd 2013 GLK 4matic and discovered one tire is wrong size!
Have them give you an extended warranty if you want to keep it covering the drivetrain or return it back.
08-05-2015, 10:39 AM
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Get it in writing, push for the free extended warranty. How's the tread on the tires? should give indication of how long its been.
This is not something the prior owner would do by choice, it must have been a service screw up pre/post sale
This is not something the prior owner would do by choice, it must have been a service screw up pre/post sale
08-05-2015, 01:36 PM
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350 GLK, C280
Actually the diameter of a 235/40R20 is 27.4" the circumference is 86.0" and the Revs/mile is 737 http://tire-size-conversion.com/tiresizes/235-40R20.htm
The diameter of a 235/45R20 is 28.3", the circumference is 88.9" and the revs/ mile is 713. http://tire-size-conversion.com/tiresizes/235-45R20.htm
So the difference is about 3.1% not 12.5%. However, even this is not good on the front differential. As it is a CPO, I would, as all else said, push for an extended warranty at least on the front diff and transfer case, as some of the difference will show up between front and back because the front will try to average out between left and right.
The diameter of a 235/45R20 is 28.3", the circumference is 88.9" and the revs/ mile is 713. http://tire-size-conversion.com/tiresizes/235-45R20.htm
So the difference is about 3.1% not 12.5%. However, even this is not good on the front differential. As it is a CPO, I would, as all else said, push for an extended warranty at least on the front diff and transfer case, as some of the difference will show up between front and back because the front will try to average out between left and right.
