Instrument to record, on a graph, vehicle trip information such as mph, rpm, stop-and-go periods.

Instrument to indicate engine speed in revolutions per minute (RPM).

A term used to describe the sticky quality of a rubber compound.

Powder lubricant to prevent sticking between tube and tire.

A combination of two axles having a common suspension.

Two powered axles in combination.

Tire and Rim Association.

A measurement of the greatest longitudinal stress a tire cord can bear without breaking.

Loss of strength of carcass cords due to heat generated in a tire.

Connecting rod between steering arms.

Adjustable connections between tie rod and steering arm used to adjust toe. See alignment.

Paint, black glossy or dull finish, to improve appearance of tire sidewalls.

The Industry Safety Council.

A black paint, compatible to tire bodies, used to enhance the appearance of a tire after retreading.

Those designations that appear on the side of a tire to indicate its basis dimensions; width and rim diameter.

 A system devised to ascertain the working capacity of earthmover tires; it is a supplement to the normal load and inflation tables.

See alignment.

An allowable variation in dimension.

Code number of the tube valves and flaps set by Tire and Rim Association.

The amount of force exerted to tighten wheel nuts, expressed in foot pounds. One pound of force at the end on a one hot lever equals one foot pound. Torque also refers to the amount of turning force supplied by the engine and transmitted to driving axle.

A steel bar attached between the frame and a moving part (control arm or axle) that acts as a spring. Any vertical movement is a twisting force on the bar which resists the movement and cushions the vehicle. It is used by some manufacturers to replace the coil spring.

Distance between centerlines of tire tread measured across axle.

The alignment of the vehicle with respect to axle centers of a vehicle being in the same plane, rear tires following front tires and trailer following the tractor, in the attitude designed. Correct tracking is when the rear wheels of a vehicle follow the same line as the front wheels.

Steepest negotiable grade where traction is the limiting factor.

The grip or friction, pull or bite between tire and ground.

Truck portion of combination or train.

Platform or container on wheels pulled by tractor. See full trailer, or semi-trailer.

Tires bouncing up and down, usually from incorrect static balance. Sometimes from running empty with high inflation pressures in trailer tires.

A non-solid driving axle used with independent suspension on some rear engine vehicles. The transmission and differential are in one unit, driving the axle.

Split power gear box transmitting drive to front and rear axles.

Additional gear box increasing the gear ratio combinations when used with main transmission or multi-speed axles.

Selective gear box providing various combinations of gear ratios.

The portion of a tire that makes contact with the road. It contains ribs, grooves, and sipes, etc., for traction, and special compounds for resistance to wear.

Raised portions of rubber that make up the tread of the tire, separated by grooves that are arranged laterally, providing traction in the forward or rearward direction.

Raised portions of rubber that make up part of the tread pattern They are often present in the shoulder area and are more or less rectangular in shape.

The measurement from the bottom of the tread groove to the top of the tread expressed in 32nds of an inch.

The continuous raised portions of rubber that run circumferentially (straight or in a zigzag pattern making up the tread on the tire.

A roller, either manual or power, used to help apply the tread rubber, remove trapped air and obtain adhesion. See stitching

Pulling away of the tread from the tire casing.

Distortion produced by rolling stresses within the tire, resulting in tread wear and rolling resistance.

Bars of rubber across tread at base of tread grooves having height of 2/32" at several spots around the tire circumference. Smooth lines appear to warn that safe tread life is exhausted.

Refers to the arrangements of the stabilizing tread plies whereby their cords form tiny triangles in the Michelin X radial truck tire.

Vehicle having three rear axles driving.

The act of cutting rubber off the tread of a tire while rotating on a truing machine to make the tire assembly round. A sometimes harmful practice which takes off tread rubber to allow for an out of round wheel, or for a tire not mounted properly.

See inner tube.

Radius of minimum tuming circle. Also an alignment angle. See alignment.

See dual mountings.

Axle having two selective gear ratios.

A trade name for a form of rayon produced exclusively for tire cords.

U-shaped bolt for attaching leaf springs to the axle.

See balance

A condition which describes less than acceptable vulcanization or curing.

Insufficient air pressure in a tire for the amount of load carried.

The use of a tire having insufficient carrying capacity for the load. Also replacing original-equipment tire size with a smaller size of sufficient capacity, thus reducing unladen weight.

A vehicle is reluctant to leave the straight ahead path while steering. Can be caused by larger slip angle in front tires than rear. Also see tire deviation angle.

The actual weight of a vehicle or combination with no payload. See tare weight.

See free radius.

That portion of the weight of the vehicle not supported by the springs; including tires, wheels, axles and brakes.

A device through which a tire is inflated. It includes a valve stem, valve core and valve cap.

A screw-on cap to seal air in the valve.

A check valve within an air valve which permits air pressure checks without undue loss of air pressure. The core should not be considered a valve seal.

Extra length added to valve stem for greater accessibility particularly on inside duals.

Spring providing variable effective length through cam action to suit load.

Rate of motion.

The act of perforating a textile bias ply tubeless tire above the beads during retreading. Thus air bleeding through the calendering can escape without forming air pockets between plies.

Process rubber by chemical means, usually in combination with heat, to improve its strength, hardness, elasticity and to effect bonding to other rubber compounds. Used in the manufacture, repair and retreading of tires.

Reference to steering where vehicle moves or rambles from a fixed course without positive control.

A visual sidewall condition which appears as cracking of the rubber. See 'OZONE CHECKING'.

Vertical distance from bead seat to bottom of drop center rim.

Manual or power device employing a drum with cable or rope for pulling objects where great power is required. Power generated by vehicle engine and transmitted through power take-off on transmission.

See alignment

Tendency of tire and wheel to hop during braking or acceleration of vehicle.

A capillary act of air escapement from the tire casing during retreading.

See retreading terms or stripping stock
That type of tread rubber that is tapered to a feathered edge on each side in order that it may be applied to the shoulder of the tire. Used only on a full retread.