1/16 or 0.0625
Slow down and make sure your tires have at least 2/32" of tread depth.
Minimum tread depth for all 4 tires is 2/32"
The standard tread depth for tires is 2/32 of an inch. It is important to maintain this depth because adequate tread depth helps tires grip the road, improving traction and handling. Insufficient tread depth can lead to reduced performance, increased risk of hydroplaning, and decreased braking ability, posing a safety hazard.
When the tread (the pattern in the tyre) is wearing thin. In Britain the law says the tread must have a depth of at least 2mm. Other countries may have different legislation.
When your tires have 2/32" tread depth left you need to replace them.
I inspect the tire and measure the tread depth.
That depends on who old/used the type is.
In Oregon there is no minimum thread depth, but just that Oregon requires that tires be in safe operating condition, without any bulges or exposed cords.
2/32
1/32
In the United States, the tread has to be 4/32 (3.17mm) or more on the front tires and 2/32 (1.58mm) or more on the back tires. rear tires can be retreaded but not the front "steer" tires.
Loss of traction poor tread depth on tires