Wheel & Tires:
Using a tire pressure gauge
Part 1. Preparation and safety
Objective
- Use a tire pressure gauge and interpret the readings correctly.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Do not inflate tires above the pressure recommended by the tire manufacturer. If you do, the tire may explode or the wheel rim may give way and cause a blowout. The result will almost certainly be personal injury.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- There are two main types of tire pressure gauges — fixed workshop gauges and portable pocket size gauges.
- The two most popular types of pocket tire pressure gauges are the pencil type and the dial type.
- The pencil type looks similar to a pencil and contains a graduated sliding extension that is forced out of the sleeve by air pressure when it is attached to the tire valve.
- The dial type has a similar fitting to the pencil type but includes a graduated gauge and needle.
- Each gauge measures pressures in either pounds per square inch (PSI), kilopascals (kPa) or bar.
- One bar is equivalent to 100 kPa and 14.5 PSI.
- One PSI is equivalent to around 7 kPa. Some gauges have scales for both units of measurement.
- Pocket type tire pressure gauges are inexpensive and more accurate than the gauges provided by service stations. Service station gauges are often damaged by weather, misuse or being run over.
- There may also be a significant difference in readings between one service station tire pressure gauge and the gauge from another service station.
- If the same pocket type tire pressure gauge is always used to check tire pressures, then there will be no variation of readings.
- The tire pressure will vary from vehicle to vehicle, its use and driver preference. Recommended tire pressures are located on the vehicle manufacturer's tire decal. The recommended maximum tire pressure is located on the tire sidewall. Never inflate the tire above the recommended maximum pressure. The tire may explode, or the wheel rim may give way and cause a blowout.
Part 2: Step-by-step instruction
- Remove the valve cap
First, remove the valve cap from the tire valve. Be sure to place it where you can find it later!
- Fit pencil gauge to the valve
Make sure the graduated sleeve is seated into the gauge body, and then push the tire gauge chuck firmly onto the head of the valve. If air escapes, adjust the angle and your hand pressure until no more air leaks out.
- Read the scale
When the graduated sleeve slides out, remove the gauge from the valve without moving the sleeve and examine the scale.
- Add the numbers
Read the bottom number, then count the marks. Add them up, and you’ll find the tire pressure
- Examine dial gauge
When using a dial type gauge, check the graduations on the dial. They may be in pounds per square inch, or if it’s a metric gauge they will be in kilopascals or bar. Many gauges have all three graduations: PSI, kilopascals and bar. Once again, remove the valve cap and put it in a safe place.
- Attach the gauge to the valve
Attach the dial pressure gauge to the top of the valve. Adjust your hand pressure and angle, so that no air is escaping from the valve.
- Read the gauge
When the needle has jumped, remove the gauge from the valve, and read the dial. The numbers are by tens, and the marks between are units.
- Reset the gauge
Reset the dial gauge to zero by pressing the button on the neck of the dial. Repeat the procedure for all wheels. Remember to replace the valve cap on each wheel as you go.
- Check your results
Check your tire pressure readings against the specifications in the shop service manual. You will also find a tire decal listing the recommended tire size and pressures. This is usually located on the driver’s door, driver’s door pillar or glove compartment lid.
Checking & adjusting tire pressure
Part 1. Preparation and safety
Objective
- Check and adjust tire pressures to correct levels.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- If you check the tire pressures after the vehicle has been driven a long distance and the tires are hot, DO NOT RELEASE this excess pressure. If you bleed the tire down to the manufacturer's recommendation, it will be under-inflated when the tire is cold or at normal operating temperature. This could cause the tire sidewall to fail.
- Never inflate a tire above the manufacturers recommended maximum pressure.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Tires get hotter as they are being driven. Driving on under-inflated tires can cause serious damage to the tires. The sidewalls are subjected to excessive flexing that can generate a great deal of internal heat.
- Check the owner's manual or the tire decal usually located on the driver's side door jam for correct pressures.
- The tire pressures should be checked when the tires are cold. On average, the pressure in a tire will increase by about 12.5 kPa for each 2°C (1 pound per square inch (psi) for each 10°F) the tire is above its normal operating temperature.
Part 2: Step-by-step instruction
- Prepare the vehicle and equipment
Park the vehicle so you can reach all four tires with the air hose. Check the recommended pressures in the owner’s manual, or on the tire decal usually located on the driver’s side door, or surrounding location.
- Check the tire sidewall markings
Check the sidewall markings on the tire for the maximum operating pressure. At the same time check the tire specifications and maximum load carrying capacity. These details can normally be found on the driver’s side of the vehicle, on a decal near the door pillar. If the tire markings do not meet the specifications of the vehicle, tell your supervisor and ask for their direction. This can have a serious effect on the performance of the tires and the vehicle.
- Check and adjust pressure
Check the pressure when the tires are cold. Remove the cap from the tire valve on the first tire. Use a reliable tire gauge to check the air pressure in the tire. A pocket type pencil gauge is ideal for this purpose. If there is a gauge attached to the air filler this is less likely to be accurate as it is more vulnerable to damage. If you need to add air, use short bursts with the air hose so you don’t over inflate the tire. Re-check the tire pressure after filling it and replace the cap on the tire valve. Repeat the process for the other tires.
Checking for tire wear patterns
Part 1. Preparation and safety
Objective
- Check tire for correct wear pattern and ensure there are no embedded foreign objects in the tread.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Some manufacturers supply an emergency rim assembly instead of a full-size spare. It is not intended for long-term use or high speed, but it must have adequate tread.
Part 2: Step-by-step instruction
- Check for foreign objects and pressure
Inspect the tires for embedded objects in treads and remove them, and look for signs of wear on all wheels, including the spare. Check the pressure in the tires.
- Check tread wear depth
Most tires have wear indicator bars incorporated into the tread pattern. Inspect the wear indicator bars. Tires should have at least one sixteenth of an inch, or two millimeters of tread remaining. The wear indicator bars are normally set at this depth. If the tread is worn down to that level or below, they are unserviceable and must be replaced.
- Check tread wear pattern
Check the wear patterns with the vehicle’s shop manual to indicate the types of wear that have occurred. Causes of uneven wear can include faulty shock absorbers, incorrect front alignment angles, and wheels out of balance. Uneven tread and bald spots can indicate over- or under-inflated tires and poor alignment.
- Check tire for damage
Inspect the sidewalls of the tires for signs of cracking from impacts with blunt objects. Carefully examine the tread area for separation. This is usually identified as bubbles under the tread area. Spin the wheel and see if it is running true. If it is wobbling as it rotates, report it to your supervisor.
Rotating tires
Part 1. Preparation and safety
Objective
- Rotate tires to meet the manufacturer's requirements.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Some tires are directional; they are designed to turn in one direction only. They cannot be moved from one side of the vehicle to the other, otherwise they will rotate against the direction of their design.
- Other tires are asymmetric; the tread differs from inside to outside. Asymmetric tires must be mounted on the rim correctly.
- The majority of tires can be mounted and run in either direction.
- Remember to adjust air pressure on each tire to recommended levels.
Part 2: Step-by-step instruction
- Prepare the vehicle
Prepare the vehicle by removing any hubcaps or lug nut covers, loosen the lug or wheel nuts while the vehicle is still on the ground, and raise the vehicle to a comfortable working position.
- Remove the tires
Consult owner’s manual for the recommended rotation sequence, and check and compare the type of tire fitted with the original specification. If the original wheels and tires have been changed for aftermarket replacements, locate the recommendations for wheel rotation according to the aftermarket manufacturer. Check to see that radial tires are not mixed with bias tires on the vehicle. If there is a mixture, the bias tires should be installed on the front and the radials on the rear.
- Rotate the tires
Note that some vehicles have smaller size tires on the front, and these must not be rotated to the rear. Normally the wheels and tires are rotated by moving the front tires to the rear, and the rear to the front. However, in some arrangements, they are moved diagonally so the procedure should only be carried out in accordance with the vehicle’s shop manual, owner’s manual or the type of tire fitted.
- Tighten the wheel studs
Refit the wheels. Screw on the wheel nuts or studs. It is a good practice to put them on finger tight first before tightening further. Do not put the nut or stud into the socket of an impact wrench and power them on directly. This practice can lead to the wheel nuts or studs going on cross-threaded. Once the nuts or studs are ready to be torqued down, refer to the shop manual for the correct torque and tightening sequence. Typically, the lug nuts are tightened in a diagonal sequence on four stud wheels, and in a star arrangement for five stud wheels until all of the nuts are tight. However, there are exceptions, so the manufacturers recommendations should be referred to. This should be done to a specification of 50% of the recommended torque for the first stage,and then to 100% of the specification at the second stage, using the same tightening sequence for the particular wheel.
Removing a tire
Part 1. Preparation and safety
Objective
- Safely remove a vehicle tire from a rim.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- An inflated tire is a pressure vessel that must be treated with care and respect. Always fully deflate the tire before performing any repair tasks.
- Keep your hands clear of the bead breaker when it is operating. It applies great force to the tire that will cause you a severe injury if your hand is trapped.
- Always use correct lifting techniques when lifting a tire on and off the tire changer.
- The tire tread comes in contact with many unknown substances that are transferred directly to your hands. For this reason it is recommended you wear protective gloves when handling tires.
- If you do not wear gloves, wash your hands after the tire change is complete and before eating.
- Always wear protective clothing and the appropriate safety equipment.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Always remove any balance weights from both sides of the rim before mounting it on the tire changer. If they are not removed, the bead remover will drag the weights around the rim causing damage to the rim face. This is particularly the case with alloy rims. The damage done by the balance weights is not repairable and usually requires the rim be replaced.
- The turntable jaws can hold the rim by grasping it from the outside or the inside. When mounting an alloy rim it is normal that they be clamped from the outside, whereas steel rims are clamped from the inside. Always check the instruction manual for the tire changer you are using for the correct method of clamping a rim.
Part 2: Step-by-step instruction
- Visual check
Before removing the tire, check the tread and sidewalls for barbs or pieces of steel belt that may cause you injury. Also inspect the tire for any obvious signs of damage. If there is any damage the tire should be discarded. Check the wheel for any balance weights and remove them with the wheel weight tool.
- Deflate the tire
Locate the valve stem and remove and store the dust cap. Using the correct tool, remove the valve core, remembering that compressed air inside the tire will escape with some force, so make sure the valve stem is pointing away from your face.
- Break the bead
Once all the air has expelled from the tire, locate the wheel in the bead breaker with the outside of the rim facing towards the blade. Locate the blade close to the edge of the rim while keeping your hands at a safe distance. Activate the bead breaker, which will force the tire bead away from the edge of the rim and over the safety ridge. Release the blade, turn the wheel one half of a turn, reposition the blade and release this section of the tire as well. Release the blade, roll the tire away from the machine and reposition it with the inside of the rim facing towards the blade. Repeat the bead braking procedure.
- Mount the wheel on the changer
Locate the wheel and tire assembly on the turntable and activate the jaws so they hold the wheel centrally. Test the security of the wheel by attempting to turn it. It should remain fast. Position the bead remover between the edge of the rim and the tire and apply some lubricant around the broken bead to assist in removal. Use a tire lever to roll the tire bead over the bead remover knuckle, and at the same time push down on the sidewall on the opposite side of the tire.
- Remove the tire
Activate the turntable so the bead is guided off the rim. Once the bead is removed stop the turntable and lift the tire slightly and remove the tube if fitted. Guide the lower bead into the rim well and using the tire lever, roll the lower bead over the knuckle and activate the turntable. The tire will come off the rim. Remove and discard the valve stem.
Fitting a tire
Part 1. Preparation and safety
Objective
- Safely fit a vehicle tire to a rim.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Over inflated tires can explode. Do not inflate the tire to a pressure greater than 300 kilopascals or 45 pounds per square inch.
- When the tire is being inflated, use an inflator that allows you to stand clear of the tire. Keep hands and body away from the area of the tire.
- When a tire explodes, the tire, rim or components from the tire changer may cause serious injury or death to any person nearby.
- Keep your hands clear of the bead breaker when it is operating. It applies great force to the tire that will cause you a severe injury if your hand is trapped.
- Always use correct lifting techniques when lifting a tire on and off the tire changer.
- The tire tread comes in contact with many unknown substances that are transferred directly to your hands. For this reason it is recommended you wear protective gloves when handling tires.
- If you do not wear gloves, wash your hands after the tire change is complete and before eating.
- Always wear protective clothing and the appropriate safety equipment.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Most tire manufacturers indicate two positions on the tire. The heavy point and the low point. The location of these points will affect the location of the tire on the rim.
- Some tires are directional. That is, they are designed to turn in one direction only. An arrow on the sidewall indicates the direction of rotation.
- Some tires are asymmetric. Their tread pattern differs across the face. These tires have an inside and an outside. This is indicated on the sidewall.
- Some tires are Asymmetric and Directional. Their sidewall will indicate both direction of rotation and tire orientation.
- Do not fit a tire that is too wide or too narrow for the rim. Check the tire manufacturer's recommendation for the correct range of rim sizes for a particular tire.
- If the tire is clamped from the outside it is necessary to release the clamps before inflating the tire.
- The turntable jaws can hold the rim by grasping it from the outside or the inside. When mounting an alloy rim it is normal that they be clamped from the outside, whereas steel rims are clamped from the inside. Always check the instruction manual for the tire changer you are using for the correct method of clamping a rim.
- Tire inflators have a spring loaded (dead man's) trigger that does not lock into position.
- Most tire changers remove and refit the tire by turning the turntable clockwise.
Part 2: Step-by-step instruction
- Examine the wheel
Check and remove any rust or dirt from the rim. Depending on the type of rim a slightly different fitting procedure may have to be followed. Always check with specifications on the tire machine you are using before proceeding with the mounting of the tire to avoid damage to the rim.
- Fit a new tubeless valve stem
Select the correct type of tubeless valve stem and insert it through the hole in the rim from the inside. Using the special tool, pull the stem through until its groove locates in the hole. Remove the valve core.
- Refit the tire
Apply some lubricant to the tire bead and rim ridges and position the tire on top of the rim. Using the guide on the bead remover, position the lower bead so that a portion of it is positioned in the rim well. Activate the turntable and guide the tire onto the rim. Once the lower bead is fitted, position the upper bead so that it is guided over the edge of the rim by the guide on the bead remover. Activate the turntable and guide the tire onto the rim. As the turntable rotates, push the sidewall down, keeping your fingers clear of the rim, so that the tire bead is guided below the safety ridge into the rim well. This will prevent the bead and tire from tearing.
- Inflate the tire
Attach the tire inflator fitting to the valve stem, stand clear of the tire and inflate it until both beads seat against the rim. Check the location of the bead indicator to make sure the bead is fully seated. If the rim is clamped from the outside it will be necessary to release the clamps so the tire can inflate.
- Do not over inflate
Do not inflate the tire to a pressure greater than 300 kilopascals or 45 pounds per square inch; otherwise tire or rim damage can occur. If the beads do not seat, deflate the tire again, reposition it, add more lubricant to the tire and rim, and start the inflation procedure again. When the beads are properly seated, remove the inflator attachment, remembering that compressed air will escape with some force, so keep your hands and face clear of the valve opening.
- Refit the valve core
Once the tire has completely deflated, refit the valve core using the correct tool. Reattach the inflator, stand clear and inflate the tire to the correct pressure for that application. Use a soft brush and apply a small amount of soapy water to the bead. If there are any air leaks they will be indicated by bubbles.
Dynamic balancing a tire
Part 1. Preparation and safety
Objective
- Dynamically balance a tire and wheel rim assembly.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Embedded objects may fly off the tire when it is spinning on the wheel balancer, so wear safety glasses.
- If the wheel balancer is fitted with a safety hood, ensure it is in place when the wheel is being rotated.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- If the vehicle has directional or asymmetric tires, ensure that they are refitted to their correct position.
- Some wheels require a specific design of wheel weight. If the weights fitted to the wheel are not the correct type, they will fly off when the wheel is turning, causing possible injury or damage.
Part 2: Step-by-step instruction
- Prepare the vehicle
Prepare the vehicle by loosening the lug nuts, and then raise the vehicle into a comfortable working position. Check that the tires fitted to the wheels on the vehicle are not mixed with both radial and bias type tires. If there is a mixture, the bias tires should be installed on the front and the radials on the rear, when refitting the wheels.
- Remove the wheels and tires
Mark the wheel in relation to its location on the vehicle and then remove it. This is so that there is no chance of mixing up the wheel’s position to the hub when replacing it.
- Mount the wheel on the balancer
Check and adjust the tire pressure before balancing the wheel. Mount the wheel and tire on the balancer, putting the inside part of the tire on first. Secure the wheel with the hub nut assembly.
- Determine balancing settings
Measure the width of the rim with a rim caliper, the location of the flange on the wheel with a gauge, and the diameter of the wheel. Input this data into the balancers computer, if fitted, in accordance to the equipments instructions. If no computer is fitted, set the data settings manually according to instructions. Lower the safety hood over the wheel.
- Check the tire balance
Turn the balancer on to spin the wheel. Read the balancing machine analysis, which is normally displayed visually on the machine, and tells you whether the wheel is out of balance, and if so how much weight to use and where to put it to balance the wheel. If the wheel is out of balance you should remove the old weights and recheck the balance of the wheel before adding new weights.
- Correct the balance and recheck
Install the weights recommended by the machines display, using the correct fixing method for the weights. The type of weight and method of fixing, depends on the type and construction of the wheel that the weight is being fitted to, so always refer to the wheel manufacturers specifications when doing this part of the job. Now re-spin the wheel to check for accuracy of the balancing job and to confirm that balance has been achieved. A reading of zero on both sides of the wheel means the wheel is ready to reinstall on the vehicle. Repeat the process for the rest of the wheels and tires.
- Refit the wheels and tires to the vehicle
Refit the wheels to the vehicle using the correct procedure, remembering to lower the vehicle to the ground before torquing the lug nuts to specification using the correct tightening sequence.
