On my ML350 I have 3 tires that are around 11/32-10/32 and a used tire around 7/32. They are all the same brand and size tire bridgestone dualer HL- Alenza 235-65-17. The reason the one tire is 7/32 is I got a blowout on the way to Death Valley and stopped at a used tire store that had a tire of the same brand and size (pretty lucky in the middle of the desert) The guy threw it on balanced and mounted for $40 bucks! So when I got back to town I was going to buy a new replacement tire and no one will sell me a new one! I went to 4 tire shops and they all say I have to buy all 4 new at 13/32 tread depth because if they are not all exactly the same tread depth on this vehicle it will destroy the transfer case or the trans or some kind of fluid clutch?? .....Never herd of this?
So whats the scoop are they pulling my chain or is this true that 3/32 will cause alot of damage??????????????????

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

They are practicing defensive repair to prevent being sued just as doctors practice defensive medicine to minimize the chances of being sued. Some 4wd systems are super sensitive to tire diameter and the 4wd system will kick in causing chatter when making slow speed tight turns.

There probably won't be damage with the 7 /32 but I'd be better off with 13/32 against the worn ones. ( And given the climate / sun / heat damage a tire that has less miles )