Most are in mm or /32 of an inch.
It is the depth of the grooves in the tyre.
If you mean tire tread depth, the minimum is 1.6mm.
That depth present on a new tyre.
The minimum tyre tread depth in the UK is 1.6mm.
Minimum LEGAL tire tread depth is 2/32nds of an inch.
UK is 1mm
The average tread depth of a new radial tire is typically around 10/32 to 11/32 of an inch. This tread depth provides good traction and performance while allowing for gradual wear over the lifespan of the tire.
Purchase a tread depth gauge from your local auto parts store. It will measure in 1/32" increments. Take measurements at the inside, middle and outside of tire treads.
It is the rubber marker within the tread to show tread depth. It is also known as a tread wear indicator
LGV's must have a tread depth of at least 1mm across 3/4 of the breadth of the tread and in a continuious band around the entire circumference
1/32
1.6 mm is the minimum