Tyre Tech and General Tire Information A punctured speed rated tyre brings with it additional considerations. While some tire manufacturers "allow" a tyre to retain its speed rating if a specified multi-step repair procedure is followed exactly, most tyre manufacturer s reason that they have no control over the quality of the repair, they cannot confirm that the tyre has retained its high speed capability. Therefore, their policy is that a repaired tyre no longer retains its speed rating and be treated as a non-speed rated tyre. Guidelines allow the repair of punctures in a tyre's tread area of up to 1/4" in diameter. Repair of larger tread punctures and to the tyre's shoulder and sidewall areas are not recommended. There are three primary considerations when repairing a punctured tyre. 1. You need to evaluate the damage the object caused as it punctured the tyre. 2. Re-establish an airtight seal of the tyre's inner liner. 3. Completely fill the path the object took through the tyre. A mushroom-shaped patch and plug combination repair is the best method of repairing a punctured steel belted radial.
Any repair attempted without removing the tyre from the wheel is improper. Without inspecting the inside of the tyre for damage comes the risk of a weakened tyre to service. Punctures in the tread area that looked repairable have upon further investigation the object has been in long enough to cut the tyre's sidewall from the inside. Without dismounting the tyre, the damage would have been missed. Plugging a tyre from the outside without removing the tyre from the wheel is improper. (If a tyre is punctured while off-roading far away from civilization and a spare tyre isn't available, a plug may serve as a temporary low speed solution that must be replaced with a proper repair as soon as possible upon returning to the road.) Additionally, any repair that doesn't completely fill the path the object took through the tyre is incomplete. While a patch on the inside reseals the inner liner, it does not fill the path of the puncture. This will allow moisture to reach the steel belts and/or the casing cords causing them to rust or deteriorate. There are many different rubber compounds used in a tyre. The tyre's inner liner uses a special rubber compound that is better at retaining air. Once punctured, the inner liner must be cleaned, buffed, cemented, patched and coated to assure its ability to retain air has been restored. This can only be done from inside, it's the reason that a plug-only repair is improper. Continuing to drive with a slow leak allows moisture to seep around the object and into the tyre. The moisture will ultimately reach the internal steel and fabric cords used to reinforce the tyre and possibly cause rust and loss of strength. To assure reestablishing a watertight seal the puncture must be cleaned with a specially designed cutting drill that removes rust and sizes the puncture properly to accept the rubber stem of the patch. Cemented in place, the stem will vulcanize with the tyre to help prevent moisture from reaching the tyre's reinforcing cords from the outside. DO NOT REPAIR A TIRE IF: 1. There is 2 32" or less of tread on any 2 adjacent grooves. 2. The tyre cord or steel belt is exposed; there are flex breaks, or severe sidewall abrasions. 3. There is any evidence of a separation in the tread area or the sidewall of the tyre. 4. There is any evidence to indicate the tyre has been RUN FLAT. DO NOT INFLATE, as reinflation could result in serious injury. Dismount the tyre and inspect for inner liner damage. 5. There are punctures or damage in the shoulder or sidewall areas. 6. Never use any rim that is bent, pitted, cracked, or worn. Remove rust, dirt, or foreign materials from rim parts. ALWAYS: 1. Inflate the tyre to maximum allowed pressure. DO NOT OVER INFLATE. 2. Check the surface and the valve for the source of the leak(s) by using water, soap solution, or leak detector. 3. Locate the puncture and circle with a crayon. 4. Remove the valve core to deflate the tyre. 5. Dismount and inspect the inside of the tyre on a well lighted spreader for inner-liner cracks, open splices, exposed tyre cord or steel belts, broken beads or bead wires, bulges or blisters, or other interior damage. 6. If any damage other than a 1 4" maximum puncture injury in the tread area is present, DO NOT REPAIR.
Ten step procedure to tyre repair 1. EXTERNAL INSPECTION Prior to demounting 1, Check tyre surface and the valve for the source of the leak(s), by using water or a soap solution. 2. Mark the injured area and totally deflate the tyre. 3. Then remove the tyre from the wheel being careful to avoid further damage to the tyre, particularly to the bead area. Place on a well-lighted spreader. (Avoid excessive spreading of the tyre or tyre beads.) 2. INTERNAL INSPECTION Spread the beads mark the puncture with a tyre crayon. Remove the puncturing object noting the angle of penetration. Probe the puncture with a blunt awl to determine the extent and direction of the puncture and remove any foreign material. If the angle of the injury exceeds 25, use a two-piece repair system (see graphic below). Repair should only be carried out in the CROWN area illustrated below. DO NOT REPAIR if injury extends into the shoulder/belt edge area and never repair in the sidewall area.
3. PREPARE INNER LINER SURFACE Clean the puncture area thoroughly with (pre-buff) inner liner cleaner. Use a clean cloth and/or scraper, according to repair material manufacturer s recommendations. Consult your local repair materials supplier for an appropriate cleaner. This step serves to remove dirt and mold lubricants that can reduce repair unit adhesion and contaminate buffing tools. 4. PREPARE INJURY CHANNEL All damage must be removed. Use an electric/air powered drill (1,200 rpm max.) with an appropriate size carbide cutter or other suitable tool. Beginning from the inside, ream the puncture channel a minimum of three times repeat from the outside. Use a probe to check for any splits in the radial plies surrounding the injury. Remove any additional damage found. 5. REPAIR UNIT SELECTION Select the appropriate size repair unit, based on repair material manufacturer's recommendations. Center the unit over the puncture and outline an area 1/2 (13mm) larger than the repair unit, so buffing will not remove the crayon marks.
6. FILL PUNCTURE For a two-piece repair Never mix products from different repair material manufacturers. Follow repair material manufacturer application recommendations. Cement the puncture channel per recommendations (see bottom left). Completely fill the puncture from the inside of the tyre with a suitable vulcanizing material or rubber stem. Without stretching the stem, cut the material off just above the inside tyre surface (see bottom right). It is necessary to completely fill the puncture to provide a backup for the patch repair unit and to prevent rusting of the steel wires or deterioration of fabric. 7. BUFFING To prevent contamination and preserve the outline, buff within the marked area thoroughly and evenly with a low speed buffer (5,000 rpm max.) with a fine wire brush or gritted rasp. Take care not to expose or damage tyre casing body (ply) cords. Buff to a velvet surface; Never buff the tyre inner liner too deep you will expose the tyre casing body (ply) cords. If you do, the tyre must be scrapped. Remove all rubber dust from the buffed area by using a fine wire brush and vacuum, being careful to avoid touching the area. Do not use compressed air to clean bonding surfaces; air lines contain contaminants such as oil and moisture, which reduce adhesion. Follow repair material manufacturer's recommendations for cleaning the buffed area.
8. CEMENTING Do not mix products from different repair material manufacturers. Apply chemical cement and allow it to dry according to repair material manufacturer's procedures. Do not use forced air or outside heat source to accelerate drying time. (In cold and/or humid climate conditions, adjust drying time.) WARNING! Do not use flammable cements near fire, flame or any other source of ignition. Explosive force and/or fire from ignition of cement could cause serious injury or death. 9. REPAIR UNIT APPLICATION Do not mix products from different repair material manufacturers. Follow repair material manufacturer's recommendations for installation instructions. The tyre must be in a relaxed position when the repair unit is installed. (Do not spread the beads excessively.) Remove and discard protective covering being careful not to touch the bonding material on the repair unit. When using a two-piece, directionally marked unit, install the unit so that the alignment is correct and centered over the puncture. Next, stitch down thoroughly with a stitching tool, working from the center out.
When using a one-piece, combination patch/stem repair unit. Do not cement the stem, instead cement the puncture channel. Next, pull the stem through the puncture until the unit slightly dimples, then stitch down thoroughly with a stitching tool, working from the center out. Remove and discard the top protective covering. Cut the fill material flush with the outer tread surface while being careful not to stretch the stem. 10. FINAL INSPECTION
IMPORTANT! A proper repair must completely fill the injury with a suitable vulcanizing material or rubber stem and a patch must be applied to the inner liner to prevent air loss. Inspect all repairs; rework if necessary. After remounting and inflating the tyre/wheel assembly 1, inspect the assembly (tyre/rim/valve) for damage or leakage. 2. Pay particular attention to the location of the repair, the beads and the valve. 3. If the tyre continues to lose air, it must again be removed from the wheel for complete re-inspection. (For tube-type tyres are sure to replace a damaged tube with a new tube.) WARNING! A patch only or a plug (stem) only is an improper repair. Improperly repaired tyres can fail while in service, such as by tread-belt separation and/or detachment, which may result in an accident causing serious personal injury or death. Tyre Sealants and OEM Mobility Kits 1. Vehicle Original Equipment Temporary Tyre Mobility Kits and aftermarket sealants such as aerosols, liquids, or gels injected into a tyre through the valve provide only temporary mobility allowing the driver to promptly reach a service location for professional possible repair. Such sealants are not considered proper repairs. Consult tyre manufacturers recommendations regarding reparability or continued use of such tyres. 2. Tyres with damage initially treated with any type of puncture sealant(s) may have been damaged as a result of being run under inflated and/or overloaded and should be inspected accordingly before repairing tyre. 3. Tyres that are manufactured with puncture sealant require specialized repairing techniques. The tyre and/or sealant manufacturer(s) should be contacted for recommendations.
Tools for Passenger Puncture Repair Repair Materials for Passenger Puncture Repair Tyre Tube Repair Procedure Instructions 1. Inflate your tube with the air compressor. 2. Push the tube under the water in the bathtub and look for bubbles. Once you find the leak, mark it with the grease pencil 3. Clean the damaged area of the inner tube with mineral spirits and cloth to make it perfectly clear to receive the patch. 4. Rough up the punctured or torn place and the area around it with the scraper included with the hot patch kit. Do this as gently as possible. Wipe away any inner tube fibers with the solvent cloth. 5. Peel off the protective backing from the patch. Press the patch over the damaged area on the tube. 6. Place the tube in the clamp so that the patch is right below the heating cup of the clamp. The heating cup contains the heating materials, and it will come down as you tighten the clamp. 7. Fill the heating compartment with the solution that came with your patch kit. Tighten the clamp until the compartment is firmly against the patch. 8. Light the solution in the compartment with a match. Allow the flame to burn out the solution. 9. Let the cup cool off until you can touch it and take it out of the clamp. 10. Allow to cool down, repeat steps 1 and 2 to check that patch has sealed Dealing with Potentially Hazardous Chemicals & Substances The FATAL Incident: A 21 year old man was fatally injured when he was overcome by fumes when dealing with chemicals associated with tyre repair. It is alleged the man was inside or partially inside an earthmover tyre where he was subjected to fumes.
The chemicals associated with tyre repair and any other tyre related activity involving glues, solvents, etc. can be harmful and even fatal if not dealt with correctly. The following minimum standards are required when dealing with tyre-related chemicals & substances. 1. Understand what you are dealing with - MSDS. Ensure that ALL of the substances you use have the appropriate MSDS information. Store all MSDS information both in the Tyre Bay Office and where the chemicals are stored. Ensure that you understand what the hazardous are, and that you have the appropriate handling techniques and PPE. 2. Understand the tasks that may involve the use of potentially hazardous chemicals. Develop a list of ALL tasks that you undertake that involve chemicals. i.e. LV tyre repair, install of tyre-tag patches, use of nitrogen, etc. 3. Chemical Storage. Store chemicals in approved Cabinets (confirm this with your supervisor). The location of your cabinet(s) is also critical do NOT store your cabinet in small enclosed spaces such as offices, shipping containers, etc. Locate your cabinet in large well-ventilated locations (i.e. under an open-air shelter, or carport-styled structure. 4. Body Position. Do NOT place yourself in an area where fumes may accumulate (i.e. in any vessel, inside a horizontal tyre; or at the top/bottom of a vertical tyre). 5. Position of Tyre. Ensure that when undertaking tyre repair that the tyre repairs/ or similar activity is conducted at VERTICAL (or near vertical) tyre equivalent to the 9 o clock or 3 o clock position. This will give the fumes an opportunity to dissipate away from the work area 6. PPE. Ensure that your PPE is in accordance with the MSDS requirements stated on the chemical container. i.e. filtered mask, breathing apparatus, goggles, etc. 7. Supervision or Buddy-System. The findings of your above risk assessments will assist with determining how much super vision certain tasks may require. This may vary from site to site. 8. Electrical Tooling. Do NOT use electrical tooling near chemical storage areas or where chemicals are being used. 9. Smoking. Do NOT smoke near chemical storage areas or where chemicals are being used. TPMS Service Procedure (tyre pressure monitoring system) INITIAL INSPECTION A. Before performing wheel service on any vehicle, check to see if the wheels are equipped with TPMS sensors. B. Following the diagnostic tool manufacturer s instructions check each sensor to ensure each is working properly and note the state of each on the service ticket.
C. If a sensor is not working properly, inform the vehicle owner that it will need to be replaced. D. Identify which type TPMS sensor is on the vehicle: SENSOR IDENTIFICATION Clamp-In sensors Have an aluminum valve stem mounted directly to the wheel through the valve hole using a special aluminum nut. Snap-In sensors Have a rubber snap-in valve stem mounted directly to the wheel through the valve hole. Typically identified by the long, black plastic cap and/or the extended brass shoulder. Banded sensors Mounted in the drop center of the wheel using a metal band typically 180 from the valve stem. Ford is the only vehicle manufacturer using banded sensors as original equipment. SERVICING CLAMP-IN TPMS SENSORS 1. Remove the tyre from the vehicle following industry recommended procedures. 2. Deflate the tyre by removing the valve core using a valve core removal tool and releasing the air completely. 3. Remove the sensor nut and push the sensor inside the tyre. 4. Break the tyre beads at 90 and 270 from the valve stem and remove the sensor from the wheel. 5. Dispose of the valve cap, core, and nut and rubber grommet. 6. Using the appropriate new service kit, replace the valve core and grommet. 7. Reinstall the sensor through the rim hole with the flat side of the sensor facing the rim. 8. Install the new nut using a torque wrench and tighten to the proper torque specification. 9. Install the new sealing valve cap. 10. Service the tyre / wheel as required following all industry and tire manufacturer guidelines. 11. Mount the tyre onto the wheel taking special care not to damage the TPMS sensor. 12. Inflate the tyre to the recommended placard pressure. SERVICING SNAP-IN TPMS SENSORS 1. Remove the tyre from the vehicle following industry recommended procedures. 2. Deflate the tyre by removing the valve core using a valve core removal tool and releasing the air completely. 3. Break the tyre beads at 90 and 270 from the valve stem and remove the sensor from the wheel. 4. Remove the screw from the base of the sensor using a T-10 torque screwdriver tool and carefully remove the sensor from the valve stem. 5. Dispose of the old screw. 6. Remove the rubber snap-in valve from the wheel as normal. 7. Attach the sensor to the rubber snap-in valve using a new T-10 TORX screw, then torque the screw to 11.5 in-lbs (1.3 Nm.) 8. Apply mounting lube to the rubber snap-in valve stem. 9. Align the sensor with the rim hole and attach a standard valve installation tool.
10. Pull the valve stem straight into the valve hole until it is properly seated. 11. Service the tyre / wheel as required following all industry and tyre manufacturer guidelines. 12. Mount the tyre onto the wheel taking special care not to damage the TPMS sensor. 13. Inflate the tyre to the recommended placard pressure and install the new sealing valve cap. SERVICING BANDED TPMS SENSORS 1. Remove the tyre from the vehicle following industry recommended procedures. 2. Deflate the tyre by removing the valve core using a valve core removal tool and releasing the air completely. 3. Break the tyre beads at 90 and 270 from the valve stem and remove the sensor from the wheel. 4. Remove the mounting clip to release the sensor from the mounting bracket. 5. Gently pry the sensor from the open end of the bracket and discard the mounting clip. 6. If the mounting band and/or mounting bracket show signs of wear or corrosion, replace with a new band and/or mounting bracket. 7. Install a new sensor using a new retaining clip. 8. Service the tyre / wheel as required following all industry and tyre manufacturer guidelines. 9. Mount the tyre onto the wheel taking special care not to damage the TPMS sensor. 10. Inflate the tyre to the recommended placard pressure. SERVICE COMPLETION 1. Using your TPMS sensor activation tool, check all sensors making sure each is working properly. 2. Refer to your Motor TPMS Guide or vehicle owner s manual to determine if a TPMS relearn is necessary. A TPMS relearn tool may be required to reset the system. 3. If necessary, follow the instructions for resetting the vehicles TPMS system. MATCHING OF DUALS Mismatched duals have the same effect of tyres as low inflation or overload. An underinflated tyre on a dual assembly shifts its share of the load to its mate, which then becomes overloaded and frequently fails prematurely. Improperly matched duals are subject to rapid tread wear because the larger tire carries more loads. Mismatched duals with different diameters will rotate at the same speed. The smaller tire then wears unevenly because it is forced to scuff over the road. The overall result is unequal tread wear for both tires. When mounting duals on a truck, there generally is some difference in the diameter of the two tyres. Mount the small tire on the inside. The outside tire wears faster than the inside tyre. As it wears its diameter will approach that of the inside tire. At the time of mounting duals on a vehicle, locate the two valves diametrically opposite (180 degrees apart) for accessibility. Hand holes on disc wheels must be located so that the inside valve is accessible.
SPACING OF DUALS Spacing between dual tyres is important. Too often, the service life by dual tyres is sharply reduced because of insufficient spacing. It is a condition caused by either: (a) Oversized tyes (b) Improper rims and wheels. Tyres mounted too close together do not allow air circulation to dissipate tyre heat. Heat increases tyre tread loss rate and reduces tyre durability. When a truck is heavily overloaded, insufficient spacing cause the sidewalls of the duals to rub together, wear off rubber, and become overheated due to continuous friction. If the space between duals is too great, there will be excessive dragging and scuffing of the outside tire each time a turn is made. Also, check overall vehicle track width to assure compliance with width laws. Note that proper dual spacing for radial tires is the same as for bias ply. Dual spacing and tyre clearance can be varied by changing spacer width.. Rim offset determines dual spacing and affects vehicle clearance and possibly overall vehicle width. Any change in offset of the inside rim will change vehicle clearance proportionally. Any offset changes of the outside rims will change the overall distance across the vehicle from outside tire wall to outside tire wall.
SPACERS Spacer installation procedure is as follows: 1. Examine spacer brand to be sure it is not damaged, bent, or distorted. It should be perfectly circular. 2. Do not roll vehicle, wheels, axle, or assemblies on spacers. 3. Position inside rim over cast spoke wheel as close as possible to the mounting level. 4. Push spacer band over cast spoke wheel with consistent pressure on both sides. Avoid cocking band. Achieve snug fit against spokes and inside rim gutter edge. 5. Turn spacer band on wheel to check concentricity. 6. Position outside rim, install outer rim clamps and tighten nuts evenly. Tighten nuts gradually in a criss-cross sequence across the diameter of the wheels. Consult rim manufacturers recommendations for proper torque range. 7. Examine clamps to be sure they have not bottomed out. Check rim edges to be sure they consistently meet the spacer band edges. 8. 8. After road service, recheck torque. Split Rims Split rims are a type of rims used on motor vehicles especially larger vehicles such as forklifts, tractors, bulldozers, trailers etc.; the way to identify split rims is to examine your wheel, if you have split rims there should be a ring around the outer edge of your rims that is separate from, but which seems connected to the outer circumference of the rims and sits around the inner circumference of the tyre; this ring has a small gap or split in it and is called a lock ring. Split rims are easily distinguished from regular rims as a regular rim is one solid structure with no additions, whereas a split rim has the lock ring. There are many warnings attached with the handling of split rims as they can be quite dangerous and here is why; the lock ring that comes with split rims has been known to fly off and becomes quite a dangerous projectile while a person inflates his/her tyres, especially because a person s face and body are so close to the rim while inflating a tyre. Split rims can fly in one of the following: Corroded or dirty rim parts, Not deflating tyres before removing them, Over-inflating the tire, Putting tubed tires on a rim designed for tubeless tyres, Damaged or mismatched rim parts. Risk control measures Only work on or remove a split rim tyre that is fully deflated or is of the type that can be removed when inflated. Only remove the nuts that secure the rim to the vehicle. Multi-piece rim with split ring (locking ring) Make sure all the split rim assembly parts are compatible and any damaged parts repaired or replaced before reassembling.
Use a remote control airline with pressure gauge and clip-on chuck so the operator can stand away from the guard or safety cage during the inflation procedure. Don't use a clip-on chuck on hoses connected directly to a compressed air line, i.e. without a pressure gauge and trigger or other control. Make sure that the tyre is inflated to its correct tyre pressure. DON T over-inflate. Correct tyre pressure can be obtained from the tyre fitment placard, which is mounted in the glove box or on the door or door pillar of the vehicle, or from the recommended inflation pressure stamped on the side of the tyre.