INTRODUCTION TO FITTING TRUCK AND BUS TYRES
Before fitting, the conformity and compatibility of the tyre must be checked. Correct fitting of the tyre, carried out in accordance with recommended operating procedures and current safety rules, provides excellent protection of individuals and equipment, and allows you to use tyres to their full potential.
A. General precautions
- Operators must always wear their usual protective equipment (ear defenders, gloves, safety boots, safety goggles, etc.)
- Operators must have a procedure to follow.
- Operators must check that the vehicle is stationary with its engine switched off, and that it is correctly stabilised (parking brake, chocks, axle stands, etc.)
B. Tyre fitting precautions
- Make sure the wheel and its components are in good condition.
- Check the tyre is compatible with the wheel, with the vehicle and with its intended use.
- Respect the positions, fitting direction, direction of rotation and any relevant instructions mentioned on the tyre sidewalls.
- Check the interior of the tyre is clean, dry and free from foreign bodies. When fitting a used tyre, check carefully that the interior of the tyre shows no signs of having been driven while under-inflated (mottling, separations).
- Change the valve joint or the valve.
- Inflate safely, following all the inflation steps. Check that all elements are in place.
- Never stay alongside the tyre being fitted. Instead position yourself in line with the tread band, at a distance of at least 3 metres.
- All these precautions are essential for new and used tyres alike.
- We recommend fitting tyres on wheels with protected valves for vehicles equipped with disc brakes to prevent the risk of the valve being damaged by an object jammed between the brake and the wheel.
Incorrect fitting can cause damage to tyres, the vehicle or people (serious or even fatal injuries).
C. Valve checking
Due to ageing and the high temperatures associated with brakes, valve joints and valve extensions are to be replaced with each tyre change. A valve cap in excellent condition is essential for maintaining an airtight seal.
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Sealing diagram for twin fitment. For this type of fitment, always position the valves facing each other.
BEST PRACTICE FOR TYRE INFLATION
This must be carried out by competent personnel using the correct equipment. Incorrect fitting can result in damage to the tyre (may not be visible at the time of fitting), tube or wheel.
Cold tyre pressure must be determined based on load, speed and conditions of use.
Michelin recommends inflating tyres using a safety cage.
You should inflate tyres in two stages:
• pre-inflate to 1.5 bar (21.7 psi)
• examine the condition of the tyre, and if in doubt stop the operation and call a specialist
• inflate the tyre to the required pressure
• place the tyre vertically in the safety cage or in an appropriate area.
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Stand in line with the tread band and at least 3 metres away during inflation.
It is important to make sure tyres are correctly balanced, as this:
• helps tyres to achieve maximum mileage performance
• protects mechanical parts from premature wear
• ensures a comfortable ride
Tightening wheels to the right torque helps ensure a good level of mechanical grip and therefore protects your safety.
A. Wheel condition:
- The condition of wheels must be checked regularly. A cracked wheel or rim must be replaced.
- Wheels and rims must not be repaired by welding.
- If welding is required, the tyre must be removed from the rim. Otherwise there is a very high risk of explosion.
- The tyre can be refitted when all elements have returned to ambient temperature.
- Before any welding on the vehicle chassis, the tyre and wheel assemblies should be removed from the vehicle.
- Before removing split rim assemblies from a vehicle, it is recommended that the tyres are deflated.
B. Before any tightening operation you must:
- the mating surfaces of the hub and wheel.
- the wheel studs and nuts.
- the condition of the fixing holes (deformation, cracks, etc.).
- the condition of the studs (deformation, state of threads, etc.).
- the condition of the nuts (deformation, state of threads, etc.).
- if necessary, remove rust and leftover paint with a wire brush.
- any burrs on the metal.
- the threads of the wheel studs and nuts and the bearing surfaces of flat or lug nuts with a drop of oil.
- never lubricate the bearing surfaces of spherical or type M nuts or washers.
4. Final tightening torque:
- Must be applied in accordance with the tightening torques and values recommended by the vehicle manufacturer.
- Remember to tighten nuts alternately diagonally according to the number of nuts.
- Tightening to the correct torque makes removal easier in the event of a puncture, does not distort the studs and keeps you safe.
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Excessive tightening is often as harmful as lack of tightening and can result in:
- deformation and/or cracking of wheel studs.
- distortion of wheel nut threads which may even lead to wheel loss.
- ovalisation of drums, etc.
After thirty minutes or a distance of 30 to 60 miles, the tightness of wheel nuts should be re-checked using a correctly calibrated torque wrench. When tightening, nuts must not be loosened and then tightened again. They must simply be checked.
CARE AND MAINTENANCE
Tyres must be examined regularly. Make sure the vehicle is stationary, the engine is switched off and it is completely immobilised before any inspection.
A. Tyre care
• Michelin advises you to examine:
- any uneven wear, perforations, cuts and deformations visible in the tread, sidewalls or bead area of the tyre.
- any rim damage with a tyre professional.
• The causes of vehicle handling problems such as pulling to left or right and comfort issues caused by vibrations should be investigated.
• If a loss of pressure occurs, you must stop as quickly as possible as running under-inflated causes thermal degradation of the tyre components.
• The tyre should be removed from the rim to identify the reason for the loss of pressure.
• Any damage must be examined by a tyre professional capable of determining whether a repair is necessary or possible.
• Repairs must be carried out by a tyre specialist who will accept responsibility for the repair.
• Before any repair, the interior of the tyre must be examined to ensure that no degradation has occurred.
B. Tyre inspection and recommendations
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Axles, from left to right: Steering (F), Drive (D), Trailer (T)
1. Tyre wear on the STEERING AXLE of motor vehicles
• The front nearside tyre wears faster than the front offside tyre of a truck driving on the left
• The front nearside tyre often has more pronounced wear on the tread shoulder due to the camber of the road and the number of roundabouts.
To even out tyre wear and use both tyres to their full potential, including regrooving, follow this advice:
• Rotate right and left tyres when half worn
• Turn the front nearside tyre on the rim
• Regroove with 2 to 4 mm of tread remaining, i.e. when 80% worn.
2. Tyre wear on the DRIVE AXLE
• As a general rule, both the inner tyres have more pronounced wear on the tread shoulder, on the inner side of the chassis.
• Several factors are at play: camber angle, type of suspension, use of the engine brake, route conditions and load.
To even out tyre wear and use all 4 tyres to their full potential, including regrooving, follow this advice:
• Rotate the inner and outer tyres (twin fitment).
• Turn the two inner tyres on their rims.
• Regroove when 80% worn (with 3 to 4 mm of tread remaining).
• Withdraw from use according to current regulations. Fit MICHELIN Remix retreaded tyres on drive axles in rear position.
3. Tyre wear on CARRIER AXLE (case of semi-trailers with 3 fixed axles)
Due to high shifting, the speed of wear of the tyres fitted to the 3 axles is not the same:
•The 1st axle is moderately penalised by the shift and will therefore have an intermediate wear rate between the 2nd and 3rd axle.
•The 2nd axle, which is not under any stress, has a very low rate of wear.
•The 3rd axle has a faster wear rate because it is the one most penalised by shifting due to the geometry of the vehicle.
To even out tyre wear and use tyres to their full potential, including regrooving, follow this advice:
• Rotate tyres between positions based on levels of wear
• Turn tyres on their rims on the 1st and 3rd axles
• Regroove when 80% worn (with 3 to 4 mm of tread remaining):
- on the 1st axle this is possible depending on use
- on the 2nd axle it is recommended
- on the 3rd axle it is not recommended
Withdraw tyres from use on the 1st, 2nd and 3rd axles according to current regulations. For trailers and semi-trailers, MICHELIN Remix tyres can be fitted in multiple positions.
C. Tyre rotation and turning on the rim
What is it?
Tyre rotation is an operation consisting of removing the tyre from one position on the vehicle and refitting it in another position.
Turning on the rim is an operation consisting of removing the tyre from the rim and refitting it the other way round. These two operations can increase tyre longevity by about 20%
Some trucks tyres have a direction of rotation which should be complied with at the start of the tyre's life to optimise all round performance. In this case, when rotating tyres, it may be necessary to also turn on their rims to maintain the recommended direction of rotation.
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D. Antisplash™ tyres
The Antisplash™ system is designed to be effective on the outside of the vehicle. The word "Outside" is written in several languages on the sidewalls of Antisplash™ tyres.
- 385/65 R22.5 and 315/70 R22.5 tyres (check space requirements before turning 385/65 R22.5 Antisplash™ and 315/70 R22.5 Antisplash™ tyres on their rims)
- 385/55 R22.5 tyres
It is possible to turn these tyres on their rims. You must check that the Antisplash™ is not in contact with any mechanical parts. To do this, the clearances must be checked with the wheels in all steering positions (from full left lock to full right lock) taking account of the variations in geometry when the vehicle is in dynamic use.
Correctly adjusted vehicle geometry helps to ensure that the tyre gives good mileage performance. Correctly adjusting all axles of a vehicle can increase tyre mileage performances by 20% on average and save on average 2% of fuel. (Source: Josam Alignment)
PRECAUTIONS FOR REMOVING TYRES
When removing a wheel from a vehicle,
if the tyre is part of a dual fitment or if the rim shows obvious signs of damage, the tyres:
- must be deflated by removing the valve core before the fitted unit is removed from the vehicle
- Comply the vehicle manufacturer's recommendations and instructions
Removing the tyre with the wheel still fitted to the vehicle
Michelin does not recommend this practice which should only be used if it is not possible to remove the wheel. If this case, deflate the tyre entirely by removing the valve core.
STORAGE AND HANDLING
A. Good tyre storage practices:
• Clean, dry, temperate and well-ventilated premises, sheltered from direct sunlight and bad weather.
• Well away from any chemical substance, solvent or hydrocarbon likely to alter the nature of the rubber.
• Well away from any object that might penetrate the rubber (metal spike, wood, etc.).
• Well away from any source of heat, flame, incandescent bodies, equipment that might give off sparks or electrical discharges, and any source of ozone (transformers, electric motors, welding sets, etc.).
• When storing in stacks, make sure the tyres are not deformed. If tyres are to be stored for a long time, rotate them (reverse the order of the tyres in the stacks), so you can take out the oldest tyres first.
• Avoid compressing tyres under other objects.
- When storing for short periods (up to 4 weeks), tyres can be stored horizontally, one on top of another, on wooden pallets. However, stack height must not exceed 1.2 metres. After 4 weeks, the position of the tyres in the stacks should be reversed. When fitted on rims, tyres should be stored inflated in an upright position or in a single layer on storage trolleys.
- For long-term storage, tyres should be stored upright in a single layer on storage trolleys with at least 10cm clearance above the floor. To avoid deformation, it is advisable to rotate them once a month.
- Tyre tubes should either be slightly inflated, dusted with talcum and placed in the tyres, or stored deflated in small stacks of no more than 50 cm in the compartments of storage trolleys with a level bottom. Slatted palettes are not suitable as they might apply pressure at particular points.
- If tubes are supplied by the manufacturer in cardboard boxes or wrapped in film, they should be left in these because the packaging provides some protection against contamination, oxygen and the effects of light.
- Flaps should preferably be placed with the tubes inside tyres, but if stored separately they should be laid flat on shelves free from contamination, dust, grease and moisture. Never hang them – this can cause deformation and elongation.
B. When handling tyres and accessories, operators must:
• Follow the company's safety instructions.
• Be equipped with their usual protective equipment for handling.
• Use instruments and equipment that will not damage the tyres.
C. Additional Michelin storage information:
• Tyres stored for more than five years must be examined by competent personnel to determine whether they are suitable for further use.
• It is strongly recommended that tyres to be stored should be inflated with nitrogen. If air is used then it must be as dry as possible before it enters the tyre. Ensure that a valve cap is fitted to the valve.
• Tyres on vehicles parked on the ground should be inflated to the normal pressure for the vehicle. Every six months, this pressure should be checked and corrected if necessary. Every four months, the tyres should be rotated a quarter turn. The tyres should be driven for a distance every year until any flat-spotting disappears.
• Tyres on vehicles suspended above the ground should be deflated to around half the normal pressure for the vehicle.
• Stored spare tyres should also be deflated to around half the normal pressure for the vehicle.
• A procedure must be put in place to ensure that tyres stored at reduced pressure are correctly re-inflated when they are returned to service.
• Any tyre that has been stored should be visually inspected by competent personnel before entering or re-entering service.