If I miss my physical deadline ? Do I lose my CDL?

In nm , they will downgrade you . Get it done now , not tomorrow !!!

 

once you get your physical and turn it into dmv it goes back to class a

 

That is correct.

 

What if you have no intention of ever driving again. Do you need to go to the DMV and get your license downgraded, or simply let it lapse?
License is good until 2028, physical expires in August.

 

So go get one, you have hundreds of examiners all over the place.

 

Check your state dmv website for a form like this.
https://www.ncdot.gov/dmv/downloads/Documents/CDL-MED-1.pdf
I would rather keep my CDL. You never know what tomorrow will bring.

 

Yes they will down grade your license to a 4 wheeler, don't know how long after the missed deadline that they will down grade you. Get it done immediately!

 

Unless the rules have changed, In Tennessee, your cdl changes to intrastate if your physical lapses.

 

Your CDL is invalid until you have a new DOT card. The state may take a few days to notice your physical expired and downgrade your CDL. Get your physical ASAP and pray you don't get pulled over for anything until your new physical is reported to your state.

I'm sure half the answers to the question are answering "can I get away with an expired DOT card" and the other half are answering "is my CDL still legal after the physical expires." Since the OP didn't specify which of those 2 questions he was asking I'm sure the "get away with it" people and the "is it legal people" will have 20 pages of heated arguments without noticing they are arguing past each other.

 

Without HazMat endorsement it is safe to just let it lapse. With HazMat in some states you need to surrender your CDL for a non HazMat CDL before your HazMat expires, not your CDL expiration, otherwise it downgrades your CDL to passenger car, sometimes even before your HM expires.