Question 1

What method should be used to adjust wheel bearings on all non-unitized wheel hubs?

Accepted Answer

The TMC method is recommended for adjusting wheel bearings on all non-unitized wheel hubs. This method is outlined by the Technology & Maintenance Council, providing a standardized procedure to ensure proper adjustment and operation of wheel bearings.

Question 2

What is the torque required for wheel installation in a ConMet unitized hub system?

Accepted Answer

The torque required for wheel installation in a ConMet unitized hub system is typically 300 lb-ft (407 N.m).

Question 3

Technician A says that all tires of the same nominal diameter have the same rolling radius.Technician B says that to determine the rolling radius of a truck tire to measure the periphery using a tape measure and divide the result into one mile.Who is correct?

Accepted Answer

Technician A is incorrect because even tires of the same nominal diameter can have different rolling radii due to variations in tire construction and wear. Technician B's method is not accurate for determining rolling radius, as it does not account for the tire's deformation under load and other factors affecting the actual rolling radius in use.

Question 4

What is used on a tire tread profile to minimize river erosion during operation on wet pavement?

Accepted Answer

Sipes are small slits in the tire tread that help to improve traction on wet surfaces by channeling water away, thus minimizing river erosion.

Question 5

Technician A says that it is only necessary to balance axle wheel ends on the steer axle of a highway rig.Technician B says that out-of-balance axle ends substantially reduce tire life.Who is correct?

Accepted Answer

Technician B is correct because out-of-balance axle ends can indeed substantially reduce tire life, not just on the steer axle but on all axles of a vehicle. Balancing is important for maintaining tire longevity and vehicle stability across all axles, not just the steer axle.

Question 6

Technician A says that the wheel bearing on a unitized hub system should not require adjustment during the life of the hub.Technician B says that periodic topping up of oil in wheel hubs is eliminated in some types of unitized axle.Who is correct?

Accepted Answer

Technician A is correct because unitized hub systems are designed to be maintenance-free, meaning the wheel bearings do not require adjustment. Technician B is correct because some types of unitized axles are designed to eliminate the need for periodic topping up of oil, as they are sealed units.

Question 7

What types of spacer ring can be used on truck cast spoke wheel assemblies?

Accepted Answer

All the listed types of spacer rings (channel, corrugated, and corrugated channel) can be used on truck cast spoke wheel assemblies. Each type serves the purpose of maintaining proper spacing and alignment of the wheel components.

Question 8

What percentage increase in fuel efficiency is claimed when all of the dual tires on a typical semi-combination rig are replaced with wide-base singles?

Accepted Answer

Replacing dual tires with wide-base singles typically results in a 2 to 5% increase in fuel efficiency.

Question 9

Technician A says that modern tires are engineered to be retreaded just once during their service life.Technician B says that the cost of retreading a typical truck tire is approximately 50% of the cost of a new tire.Who is correct?

Accepted Answer

Technician B is correct because the cost of retreading a truck tire is indeed about 50% of the cost of a new tire, making it a cost-effective option for extending tire life. Technician A's statement is incorrect; modern tires, especially those used on commercial trucks, can often be retreaded multiple times if they are properly maintained and inspected before retreading.

Question 10

Technician A says that after replacing the drive axle tires on a highway tractor,the new revolutions per mile data must be programmed to the chassis data bus.Technician B says that the previous programming data is still valid providing the tires are of the same nominal dimension.Who is correct?

Accepted Answer

Technician A is correct because the revolutions per mile of the new tires can differ from the old ones, even if they are of the same nominal size, due to variations in tire design, tread pattern, and manufacturer specifications. This data is crucial for the accurate operation of systems relying on wheel speed inputs, such as ABS, traction control, and vehicle stability systems. Technician B's assumption that the previous data remains valid is incorrect because these slight variations can impact the vehicle's performance and safety systems' accuracy.

Question 11

When using the TMC recommended practice (RP 618A)method of setting bearing endplay on commercial truck wheel ends,what is the first step torque setting usually specified as?

Accepted Answer

The answer of When using the TMC recommended practice (RP...

Question 12

A truck tire is resisting seating at the bead.Technician A says that a metal ring inflation aid and compressed air should be used.Technician B says that a shot of ether and a match should do the trick.Who is correct?

Accepted Answer

Using a metal ring inflation aid and compressed air is a safer and more appropriate method for seating a tire bead than using ether and a match, which is dangerous and not recommended.

Question 13

Technician A says that automatic tire pressure control systems (TPCS)can often pay for themselves during the life of a truck due to reduced tire costs.Technician B says that TPCS systems must be spec'd to new truck and may not be retrofit to current trucks.Who is correct?

Accepted Answer

Automatic tire pressure control systems can indeed reduce tire costs by maintaining optimal tire pressure, which can lead to longer tire life and better fuel efficiency, thus potentially paying for themselves over time. However, TPCS can often be retrofitted to existing trucks, not just specified for new ones, making Technician B incorrect.

Question 14

Technician A says that a truck wheel that is just a couple of ounces out of balance can result in an uncomfortable ride and vibration.Technician B says that the centrifugal thrust created by an out-of-balance tire is neutralized when the tire is loaded.Who is correct?

Accepted Answer

Technician A is correct because even a small imbalance in a truck wheel can cause noticeable ride discomfort and vibration. Technician B is incorrect because the centrifugal force caused by an out-of-balance tire is not neutralized by loading the tire; the imbalance can still cause vibration and other issues regardless of the tire's load.

Question 15

Technician A says that the mass (weight)of a truck axle end includes the all of the components that rotate.Technician B says that is not necessary to balance truck wheel ends because the manufacturing process ensures that new truck tires are already balanced.Who is correct?

Accepted Answer

Technician A is correct because the mass of a truck axle end includes all rotating components. Technician B is incorrect because new truck tires may not be perfectly balanced due to manufacturing variances, and balancing is necessary for optimal performance.

Question 16

After completing a TMC wheel end adjustment which of the following confirms that the adjustment is as specified?

Accepted Answer

The correct confirmation for a TMC wheel end adjustment is an endplay of 0.001-inch to 0.005-inch (0.025 to 0.127 mm) measured with a dial indicator. This range ensures that the wheel end is neither too tight (which could cause overheating and bearing failure) nor too loose (which could lead to wheel detachment or uneven tire wear).

Question 17

What tool(s)should be used to install a typical truck wheel seal?

Accepted Answer

A seal driver and hammer are typically used to install a truck wheel seal to ensure it is seated properly without damage.

Question 18

Which of the following methods should be used to check wheel runout on a mounted tire?

Accepted Answer

The answer of Which of the following methods should be...

Question 19

When mounting a set of duals to a cast spoke wheel,where should the spacer ring be placed?

Accepted Answer

The spacer ring should be placed between the inboard and outboard tires to ensure proper spacing and alignment of the dual wheel setup. This helps in distributing the load evenly and maintaining the structural integrity of the wheel assembly.

Question 20

Technician A says that dynamic balancing of axle ends has been proven to improve fuel economy.Technician B says that dynamic balancing of wheel ends reduces suspension maintenance costs.Who is correct?

Accepted Answer

Dynamic balancing of axle or wheel ends can indeed improve fuel economy by reducing rolling resistance and can also reduce suspension maintenance costs by minimizing vibrations and uneven wear on suspension components.

Quiz 27: Wheels and Tires