Tires Tires have several characteristics that are important in understanding their design. Red = on unit test

Tire Vocabulary Belt 9.Patch Hydroplaning 10.Bead Radial-ply 11.Tread Bias-ply 12.Uniform tire quality Profile grading system Aspect ratio 13.Inflation Load index 14.Load range Drop center 15.Tread wear indicator

Tire Characteristics Traction : dry, wet, mud, ect Ride – comfort & feedback Handling - response Rolling resistance – fuel economy Noise Tread wear High speed capability

Taping a rubber tree to get natural rubber.

Synthetic rubber Most of the rubber used in modern tires is synthesized in a laboratory.

Tire construction: The BEAD The bead is made of about 10 strands of 16 gauge steel wire wrapped in a circle. The cord material in the body of a belted radial or radial ply tire runs from one bead to the other across the top of the tire The bead acts like a foundation for the ply and the rest of the structure.

The PLY STRUCTURE Gives strength to the tire. Made up of nylon, polyester or other flexible fabric. Number of ply’s determines strength / stiffness of sidewall and load capacity of the tire. Can be radial or bias Bias ply tires are old technology and hard to find.

The SIDE WALL The side wall supports the weight of the vehicle. The Aspect ratio & # of Ply’s affect the stiffness of the sidewall. All tire parts are Vulcanized. Vulcanizing is the process of heating rubber under pressure to mold the rubber and help it flow and bond with other tire parts.

The Belts Located directly under the tread Made of steel, fiberglass or another composite material. Sometimes called “under tread” The Belts support and give strength to the tread.

The Inner Liner Seals the inside of the tire so it will not seep air. Acts like an inner tube Never use an inner tube on a tubeless tire.

The Fillers Reinforces the area around the tire bead . Sometimes called chafer strips

Tire Valve Used to put air through the rim into the tire. Contains a small valve that can be removed or depressed to release air from tire.

Load Range All tires have a maximum safe carrying capacity. The load range is indicated with letters of the alphabet. Load range A = approx 750lbs Load range B = approx 1300lbs Load range E = approx 3000lbs Load range will be on sidewall of tire.

UTQGS UTQGS stands for : Uniform tire quality grading system. This system is used to rate the tires quality in three categories: 1.tread wear 2. temperature resistance 3. traction

UTQGS By law all ratings are molded into the sidewall of the tire. Tread wear rating : the higher the # the longer the tread life. 180 is common #. 180 = around 40,000MI of life. Traction rating: A B C. A is best (in wet weather) Temp resistance rating : A B C. A is best (tires ability to not build heat)

Speed rating The highest speed the tire should be continually operated N= 87 mph H=130mph ZR = above 149mph y = 186 mph

Tire Information By law all tire info must be on the placard and embossed into the sidewall of the tire.

Tire placard

Identifying tire size The metric tire size system is the most common. An alpha/numeric system is used to describe the tire. This info is always printed on the side of the tire. Often the largest letters & numbers on the side of the tire.

Metric tire size system: Example: P 205 55 zR 14 The P stands for: Passenger car The 205 is the tires section width The 55 stands for: Aspect ratio 55% of section width is section height The Z stands for: tire speed rating The R stands for: Radial tire The 14 stands for: Rim diameter (inches)

Tires Part 2

Safety Rims Safety rims have small ridges built into rim These ridges are to keep the tire on the rim at all times. The tire bead must be forced over the safety ridges to remove the tire from the rim.

Dropped Center The center of the wheel is made so it has a smaller diameter than the rim. The wheel has a dropped center so the tire can be removed without damaging the bead. During removal & installation the bead of the tire must be pushed into the dropped area .

Dropped center

Tire Inflation Over inflation of tires increase tire tension and prevents proper deflection of the sidewalls. This results in wear in the center of the tread.

Tire Inflation Under inflation is Very dangerous! A tire that is under inflated will build excess heat. This will cause the tire to de-laminate or de-vulcanize. Tire wear will be dramatically increased! Follow recommended inflation pressures on tire side wall. Fuel mileage will suffer. All Tires will slowly leak air.

De-vulcanizing due to under inflation.

Tire Problems

Dynamic Balancing When a tire is spinning it tends to move from side to side if it is out of balance. Wheels that are not balanced cause the car to shimmy or vibrate when moving. To dynamically balance a tire weights are placed on both sides of the rim.

Static balancing Static balancing is done by placing weight on one side of the tire only. A tire badly out of static balance will jump up and down as the tire go’ s down the road.

Tread wear indicators Tread wear indicators are a raised portion of rubber in the tires grooves. When the tire wears to approx 4/32 of an inch a solid bar forms across the tread surface. When any part of the bar is even with the tread the tire is no longer legal to use.

Tread wear Indicator

Tire Alignment Problems with tire alignment will cause the tires to wear excessively. Camber wear will cause wear on the shoulder of the tire. Toe wear will cause a scuffing or feather edge to occur on the edge of the tread blocks.

Tire alignment wear patterns.

Camber wear

Checking Toe Angle

Tire Rotation Rotating tires will maximize there life. Front tires tend to wear more than backs (unless you’re a teen in a muscle car) There are two recommended rotations.

Lug nut torque. Lug nuts hold your wheel-tire assembly on your car. Always use a Torque wrench to tighten your wheel lugs. Look up torque spec,s in a reference source. Typical torque spec,s: small car: 80 Ft. lbs. Large car or truck 100 Ft. lbs. + To tight = broken wheel studs. To loose = wheel comes off vehicle. Look up those spec,s.

Tire Repair When a puncture occurs in a tire it can typically be repaired by patching or in the case of a large hole be plugged. Never repair a tire with structure damage.

Remove nail or screw only after marking on inside & outside of tire.

Results of Patching a structurally damaged tire:

You can not patch the sidewall of a tire The sidewall flexes to much and the patch will likely fail!

Lift & support the vehicle your working on safely !!!

Good luck with your tire test!