Whats the minnimum tread required on drive tires?

Winter tread depth:

Allstate Ins Co: "...If sleet, slush and snow-covered roads are in your future, replace tires when they reach approximately 6/32″ of remaining tread depth to maintain good mobility. To check, place a penny into several tread grooves across the tire. If the top of the Lincoln Memorial is always covered by the tread, you have more than 6/32″ of tread depth remaining and should be safe for any sort of winter road conditions..."

Consumer Reports states, "...Unfortunately, 2/32 of an inch may be too late if you drive in rain or snow. Based on our tests of new and half-tread-depth tires, you may want to consider shopping for new ones on your car or truck closer to the 4/32-inch groove depth. For more information on this..."

Myself, several years back i recall reading thru several mtn.State publications on winter driving recommendations: tread depth 6/32" min. However, when looking for those same publications im finding their all stating, the same verbage, FMSCA tire regulations steers 4/32" & drives 2/32". With a minor difference by adding," more tread would be even better".

 

I know at Navajo, we pull steers at 8/32nds and drives at 7/32nds (although we can let it slide until 6 if need be), and then those tires go to runout for trailers. Which I think it a sound policy.

 

Define "bad conditions".

 

I have the answer from an owner operator's view.
Drive until they are slick, then replace them with new tires not recaps.