The minimum tyre tread depth in the UK is 1.6mm.
Minimum tread is 10" and maximum riser is 7.75".
Minimum tread depth for all 4 tires is 2/32"
If you mean tire tread depth, the minimum is 1.6mm.
1.6 mm is the minimum
Minimum LEGAL tire tread depth is 2/32nds of an inch.
Nosing is not taken into account when calculating initial stair set-out, but added later. The rise of a residential stair in the US is 8" and the run is 10" with a nose of 1". This means that the tread depth is 10", the height from stair to stair is 8" and the tread sticks out 1" over the the tread below. It is still 10" from front to back. A commercial stair is 7" rise, 11" run, 1" nose.
4/32nds of an inch
UK is 1mm
Normally 7" rise and 11" run.
1mm according to UK law
in Manitoba we fail them at 3/32"