Is this safe or a warning sign?

Dot told me once years ago if the outer wear bar is gone it doesn’t matter how much tread the rest of the tire had its a oos .. he’s at that point pretty much

 

Well, THAT was a dumb response. Obviously this refers only to CARS, as I've NEVER known of a commercial truck that had front coil springs. As usual, you can't expect knowledgeable answers from a bunch of randos on an internet forum...

 

This is my understanding as well. If any part of a tire tread measures less than minimum - 4/32" in this case - you can be cited. Now with other tires, I personally might press the issue a little, but with a stear? However if a boss tells a driver something is ok and the driver thinks it isn't, that's a tough situation.

 

I always thought 'major tread groove' excluded the decoupling groove, but if a decoupling groove is worn down completely, my opinion is it's time to fix whatever's going on regardless of DOT lol.

Any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4⁄32 of an inch when measured at any point on a major tread groove. The measurements shall not be made where tie bars, humps, or fillets are located.

Once it's to that point, there's not much to be had out of the tire at that position anyways. Would be better served on a local trailer or thrown on a spare tire rack IMO. And DOT has their own opinions sometimes regardless of the regs lol. I guess it's what's interpreted as a major groove for the specific officer.