[4] West Coast Lumberman. October, 1919. Page 25. The non-skid or caterpillar tire may well be used on heavy grades or where the traction is very poor, the general opinion being that it gives a firmer grip on the road and makes it safer to handle the truck in wet weather. There is no standard width of tread for truck wheels. The widths usually used on the drive wheels of the logging truck and the wheels of the trailer are twelve and fourteen inches, respectively. The use of tires of smaller width on either trailer or truck cannot be recommended. The wider the tires on the trailer, the better it is both for the life of the equipment and for ease in handling the load. When the surface of the giant tires becomes worn down so that the grooves become very shallow, it is desirable to have the tires re-grooved. They will last a great deal longer if this is done and will also give better traction on the road. The groove makes the tire lobes act separately on the uneven places in the road so that only one lobe is subjected to the strain of the irregularities instead of the whole tire. This is also true with reference to the strains that are set up internally due to the twisting of the rubber. LAWS GOVERNING THE OPERATION OF MOTOR VEHICLES The Laws governing the operation of motor vehicles upon the public highways of the State of Washington are contained and summarized in Senate Bill No. 220, Session of 1921 of the Legislature of the State of Washington. They include the following provisions governing the operation of motor trucks and trailers: (a) Chapter 153 of the laws of 1913 and Chapter 142 of the laws of 1915 are repealed. (b) Motor truck vehicles weighing less than 1,500 pounds must pay an annual license fee of ten dollars ($10.00); Trucks weighing more than 1,500 pounds and not to exceed 6,500 pounds, ten dollars ($10.00) plus forty cents per hundredweight for all in excess of 1,500 pounds and in addition thereto fifty cents per hundredweight at the rated carrying capacity. Motor trucks weighing more than 6,500 pounds must pay a license fee of ten dollars ($10.00) plus fifty cents per hundredweight for all in excess of 1,500 pounds and in addition thereto fifty cents per hundredweight at the rated carrying capacity. Trailers =used as trucks= shall be classified and rated as, and shall pay the same fees as hereinbefore provided for motor trucks of like weight and capacity.