I dunno.

I'm 170, run my 28s at 80F/90R. I took my bike past the end of the pavement on a MUP last week, just for a trial run to see if I would need to run my 34mm CX tires on a longer ride coming up. I was pleasantly surprised to find they took the gravel just fine.

Mind you, this is the fairly small stuff packed into stone dust. Your gravel may vary.