Tires and Wheels Objective: After completing this lesson the student will be able to explain the construction and the proper inspection of tires and wheels. Be able to diagnose wear patterns and driveability problems associated with these units. Balance tires using the proper methods.

Tires and Wheels  Tires  The purpose of a tire is to Provide a point of contact to road surface Provide traction for acceleration and deceleration Give an initial cushioning effect Support the loaded weight of the vehicle

Tires and Wheels  Tread Wearing portion of tire Has grooves which separate tread ribs Tread pattern will vary to suit needs Minimum of 1/16” (2/32”) tread depth Wear bars located in grooves indicates when tread wear is below minimum specs (tire needs to be replaced)

Tires and Wheels  Sipes Grooves meant to channel away water

Tires and Wheels  Tread pattern will vary to suit needs Highway (optional: directional tires) All-weather Mud and snow

Tires and Wheels  Beads Steel cords or wires which form a hoop at point where tire mounts to rim Body plies wrap around beads Stiffest part of tire If damaged during mounting or demounting can cause sudden failure (tire mounting lubricant should be used)

Tires and Wheels  Sidewall Rubber which protects sides of tire carcass Extends from bead to tread area

Tires and Wheels  Inner liner Used on inside surface of tubeless tires Made of soft, leakage resistant rubber Will resist rapid pressure loss if punctured

Tires and Wheels  Tire Repair  Use dunk tank to inspect for leaks  Mark injury then remove nail or object from tire  Tire should be broken down for inspection Check internal condition of tire Use caution when checking inner liner of tire (sharp object may be protruding) WARNING!! Be careful of temporary aerosol type tire repair products.

Tires and Wheels  Repairs can be made to holes in tread area which are 1/4” or less Do not attempt repairs in sidewall area If tread or ply separation is evident or any bead damage exists replace tire - do not attempt repair

Tires and Wheels  Select repair material Plugs are not a permanent repair Vulcanized patch on buffed inside surface is a permanent repair Plug/patch combination (head-type) will fill injury and seal with a patch chemically (permanent repair) CAUTION!! Do not gouge inner liner or expose casing fabric

Tires and Wheels  Lightly buff inner liner; do not expose casing fabric Good job

Tires and Wheels  Put tire glue over the entire buffed area.  Place tire patch equally over the hole.  Run stitching tool over the patch.

Tires and Wheels  Re-install tire and test finished repair WARNING!! Never inflate tire more than 40psi to seat beads. Never stand, lean or reach over tire assembly during inflation. If tire will not seat on rim, deflate, lubricate beads and try again. After tire beads seat, air pressure may be increased above 40psi to operating pressure. Never install tire on damaged or welded rim Inflate to proper PSI

Tires and Wheels  Radial ply Body plies run from bead to bead at 90° to tire center line No crisscross - so sidewalls are more flexible and heat build up is reduced Belts under tread area stabilize contact area Radial tires run cooler, last longer, provide better fuel economy and are safer

Tires and Wheels  Tire Codes  Example: P205/55R16 91W M + S P - passenger 205 = section width (millimeters) section height 55 = section width R = radial construction type 16 = rim diameter 91W = service description (load index and speed rating) M + S = Good for Mud and Snow

Tires and Wheels

 Tire Load Index Part of the service description EXAMPLE: Load index: a tire with a load index of 35 PSI has a maximum capacity load of 1279 lbs. To obtain maximum capacity, the tires must be matched up to correct rim.

Tires and Wheels

 Ply Ratings  P-Metric Standard load P-metric will not show a load range Standard 35 PSI

Tires and Wheels  Light truck LT-metric, LT-numeric and flotation tires will list load range letter (LT245/75R-16E, 7.50R-15D, 31X10.50R-15C) XL on a suffix will indicate Extra load (Ex: LT245/75R-16XL) 41 psi will increase load capacity B = 4 35 PSI C = 6 50 PSI D = 8 65 PSI E = PSI F = PSI

Tires and Wheels WARNING!! High pressure tires require high pressure type rubber valve stem or metal type stem

Tires and Wheels  Tire Inflation  Most common cause of short tire life and tire failure  Low tire pressure will flex sidewalls excessively and overheat Causes ply separation Increase rolling resistance and reduce fuel economy  Always check and adjust tire pressure cold per MFG specs. For every 10° of ambient temperature change = 1 PSI tire pressure change Caution: Never bleed air from a hot tire

Tires and Wheels  Advantages of proper inflation Traction Ride comfort Fuel economy Tire mileage

Tires and Wheels  Tire Inspection  Safety must be first thing on your mind when working on tires Air pressure contained in a tire has enough power to kill you if tire or rim fails  Inspection and diagnosis of tire related problems falls into several areas Steering Suspension Alignment Tire problems (Balancing)

Tires and Wheels  Selection of replacement tires Refer to vehicle owner’s manual for recommended type of tire Consult tire placard sticker on door post or glove compartment as to proper size and inflation pressure If not possible to match OEM size - use chart from tire dealer or (RMA) Rubber Manufacturer’s Association for comparable tire Replacement tire must have at least load capacity of original

Tires and Wheels Use only tires listed by manufacturer as original or optional for model Wrong tire size/height can change VSS input and performance of ECM  Tire mixing On AWD vehicles use tires of same construction and profile on all axles (consult OEM for specs) If profiles differ use lower profile tires on rear When installing tires on a limited slip axle they must also be matched for wear

Tires and Wheels  Tire Inspection  Tire wear patterns Excessive wear on shoulders or outer edges Improper inflation (under) Lack of rotation Camber roll Excessive wear on center section Improper inflation (over)

Tires and Wheels Excessive wear on one side of tread Worn suspension components (camber) Feathered or saw-tooth tread Improper toe angle Irregular depressions or bald spots Alignment Balance of tire

Tires and Wheels Cupped or scalloped depressions Steering components Alignment Suspension Balance of tire Cracked ribs Overloading, highs speed driving Excessive deviation of tire pressure from OEM

Tires and Wheels  Tire rotation Follow OEM recommendations for rotation of tires (when there is no recommendation, rotate at 6 to 8 thousand mile intervals. LR RR

Tires and Wheels  Mounting & Demounting Tires  Failure to follow proper procedures may result in personal injury  Follow machine manufacturer’s operating instructions  Never mount damaged tires, tubes or rims

Tires and Wheels  Always be sure tire is mounted on correct size rim and type of rim WARNING!! Truck rims of 16” and 16.5”. Tires can be mounted on either size and inflated. This improper installation will cause the tire to come off the rim with explosive force and cause injury or death

Tires and Wheels  Never install tube as substitute for proper repair  Always use radial tube in radial tire  Never use tube larger or smaller than tube was designed for  Use caution when demounting tires with air pressure sensor Breaking bead at wrong place = buying new sensor ($$$) Note: All vehicles sold in America by 2007 will have air pressure sensors in the wheel.

Tires and Wheels  Wheels  Wheels provide a mounting point for the tires to the hubs. Wheels are constructed with various rim diameters and widths, bolt patterns, back spacing and materials to suit different applications  Drop center type Drop Center

Tires and Wheels  Construction Steel Multi piece (alloy and steel) Special cast type (aluminum alloy) Directional (specifically made for cooling of the brakes) Stationary (EX: Vipers and Corvettes)

Tires and Wheels  Parts of wheel Rim Flange Tire bead area Drop center section Safety ridge

Tires and Wheels  Inspection Radial and lateral runout Cracks Broken welds or loose rivet Bad holes (elongated) Improper lug nuts (use proper torque specs and procedures)

Tires and Wheels  Ranging from twelve inch and larger diameter rims are OEM and aftermarket automotive sizes Measure across diameter of rim from bead seat to bead seat 5” to 18” widths OEM and aftermarket

Tires and Wheels Wheel offset and backspacing Watch out with very deep dish (negative offset) wheels on front of car that already had positive scrub radius: lots of wheel kick, instability with a flat tire or brake grab. Could pull the steering wheel out the driver’s hands!

Tires and Wheels  Tire/rim matching Wheel manufactured with low point Valve stem hole drilled at low point Mount tire with identification at rim low point Note: Not all tires will have position mark, if position mark exists, mount in phase with valve stem.

Tires and Wheels

 Split rims (used on trucks) During inflation extreme care must be used!!! WARNING!! Inflate inside a safety cage, ring may fly off with lethal force If tire explodes in cage, cage must be replaced!!!

Tires and Wheels  Inspection of hubs Look for cracks Check for loose bearing cups Runout (lateral or radial) Replace if bad - there is no repair of hub Mounting studs are normally pressed into hubs Damaged studs or nuts should always be replaced Specialized tools are available to install studs

Tires and Wheels  Wheel mounting torque patterns Knowing the wheels lug pattern is very important in matching alternate or aftermarket rims to a vehicle. It may be 4, 5, 6, 7, or 8 lug rims.

Tires and Wheels  Tire Balance  Proper tire balance offers smooth ride, extended tire life and less suspension wear  Two major effects of imbalance Wheel tramp (static) Wheel shimmy (dynamic)

Tires and Wheels

 Static balance Weight equally distributed around axis of rotation Static imbalance will cause tire to bounce up and down as it rotates This imbalance can occur at high and low speeds

Tires and Wheels  Dynamic balance Weight equally distributed on each side of center line of tire Dynamic imbalance will cause tire to wobble and shimmy as it rotates This imbalance will occur most often at high speeds starting at 40 mph and get worse as speed increases

Tires and Wheels  Preparing tire for balance Tires should be marked for position on vehicle Remove rocks from tread Inspect wear pattern Check for any carcass defects Tread separation Bubbles or blisters Cuts or dry rotting Report any damage foundReport any damage found Remove all existing wheel weights Mount wheel safely on balancer

Tires and Wheels  Refer to the following in regards to wheel balancer and weights  Place tire on balancer Pick the correct cone and tighten down the retainer drum

Tires and Wheels  Measure the distance from the tire to the machine and place it into the machine.  Measure the width of the tire and do the same

Tires and Wheels  Input the size of the rim and place the lid down Some machines have automatic starting and some are manual

Tires and Wheels  When the wheel balancer is spinning, it is analyzing the tire as to where to place the weights to stabilize the tire on a dynamic basis. This is telling the technician to place 1 oz. on the inside,.75 oz. on the outside.

Tires and Wheels  Lift the lid of the balancer and rotate the tire until the light aligns with the center.

Tires and Wheels  Place the weight(s) on the tire where the machine tells you to put it. Align it with the machine’s marker.  Choose the weight that coincides with the rim (aluminum, steel, etc.)