Tread Depth/Wear Marks/Tire Replacement

As Don said. Every make/model of tire could be different, traction handling. The summer tires for the CRV, with 50% tread left were scary slippery on damp roads when the temperature got down to 40•F. My dedicated winter tires have more traction on ice and snow

Ken

Replace at minimum at the wear bars. But if they get the least bit squirrly in the wet dump em.