Lug nuts play a crucial role in securing wheels to the hub, ensuring safety and stability on the road. When it comes to semi-trucks that transport multiple tons of goods across vast distances, the number of lug nuts is significantly higher compared to standard vehicles.
How Many Lug Nuts Does a Semi-Truck Have? Semi-trucks have 10 lug nuts per wheel, which means a total of 180 for an 18-wheeler truck. 2-piece flanged lug nuts have torque requirements of 460-510 ft-lbs. They should have physical dimensions of 33mm with a thread size of M22x1.5.
This article will explore the number of lug nuts in a truck wheel assembly, torque requirements, sizes, types, and the importance of maintaining their integrity. Additionally, we’ll discuss the potential hazards of driving a truck with missing lug nuts and state regulations governing these essential fasteners.
Number of lug nuts on a semi-truck
There are 10 lug nuts per wheel on a semi-truck to secure its wheels in their place. Therefore, the one with 18 wheels will typically have a total of 180 lug nuts. In comparison, pickups have 5-6 lug nuts per wheel.
The difference is because of the fact that it has to haul heavier loads in the range of 20-25 tons as compared to pickup trucks with a loading capacity of 1-2 tons.
Their higher numbers help them to ensure better weight distribution, stability, and redundancy.
Moreover, it prevents them from snapping due to overload and damage if a wheel comes out due to broken or missing lug nuts.
Torque requirements of lug nuts on a semi-truck
You must tighten these lug nuts according to the recommended torque requirements from the manufacturer.
This value can vary according to the loading capacity, nut type, and manufacturer. 2-piece flange nuts compatible with the semi-trucks have a torque requirement of 460-510 ft-lbs.
After securing them on the wheel studs, you should use a torque wrench to ensure that the torque value is according to recommended settings.
Moreover, after driving for 100 miles when installing the lug nuts for the first time, recheck their torque settings, as they can become loose after the initial stresses on the road.
After installing them to recommended torque values, you can use small yellow-colored plastic indicators on the lug nuts.
If you observe any change in their pattern, you can tell what specific lug nut is loose. Over-torquing them can damage the studs or break the lug nuts.
Size of lug nuts on semi-trucks
The size of lug nuts can vary according to the design and type of wheel. Usually, flanged lug nuts are compatible with hub-piloted wheels and have a hex size (diameter) of 33mm (1-9/32 inches).
They have a flange diameter of 46 mm (1-13/16 inches), height of 30mm (1-7/32 inches), and thread size of M22x1.5.
Therefore, they have a nominal diameter of 22 mm, which is the outer diameter of the threaded section of the fastener, and the distance between two adjacent threads is 1.5mm.
The larger size provides increased strength and durability to semi-trucks to withstand the heavy loads and challenging conditions that these trucks often encounter.
Types of lug nuts on semi-trucks
Multiple types of lug nuts are available, categorized based on their head shape and seat design. You will find types like conical, mag, spherical, and flanged seat designs as well as styles like duplex, extended thread, and flat seat.
However, 2-piece flanged lug nuts are most suitable for use with semi-trucks. They have a washer-like flange at the base, which provides additional support and helps distribute the load evenly.
Therefore, they are recommended for use in heavy-duty applications like these heavy vehicles to ensure a stable and secure wheel attachment.
However, stud-piloted wheels are not compatible with a flange welded with the lug nuts base, and the nut directly makes contact with the wheel or a washer to increase the contact surface between them.
Semi-truck lug nut covers
Lug nut covers are decorative accessories designed to enhance the appearance of the semi-truck wheels and protect them from moisture, dirt, or debris.
They come in different styles and designs according to their installation mechanism and material of construction.
Mostly they are made of aluminum, carbon steel, or chrome to ensure their corrosion-free working.
According to their installation method, you will find them in 2 types: threaded and snap-on.
Threaded covers are suitable for installation with studs having a gap of about ½ inch between the lug nut and threaded tip.
Otherwise, you have to use snap-on covers that you can easily install by simply pushing them on the lug nuts.
Do all wheels of a semi-truck have the same lug nut pattern?
Most semi-trucks have the same lug nut pattern for all of their wheels. It simplifies the process of replacing or rotating tires and allows for interchangeable spare wheels in case of emergencies.
There is a difference in terms of their visibility, as front wheels have prominently visible lug nuts protruding out the surface of the wheel.
At the same time, the rear ones installed on dual wheels are not clearly visible and seem hidden inside the wheel groove.
It is because the front of the truck has single wheels as they have to bear less load and are also fitted with brakes and other components necessary to steer it.
However, rear ones have dual wheels fitted on the single axle in such an arrangement that the outer wheel is in the flipped position of the inner wheel to increase the contact area between the two and mount them on a single set of studs and lug nuts.
Therefore, lug nuts are inside the concave side of the 2nd wheel and, hence, not clearly visible. Overall both sets of lug nuts are the same in their numbers, type, and physical dimensions.
Difference between lug nuts and wheel nuts on a semi-truck
Both wheel nuts and lug nuts are two terms that you will hear interchangeably in hardware stores for the fasteners to secure the wheel with the hub.
Therefore, you may find it confusing whether both are the same or if there are any differences between the two.
Wheel nuts is a broader term for different types of nuts or bolts that are part of the wheel mounting system, including stud nuts, hub nuts, axle nuts, or even wheel bearing nuts or spindle nuts.
On the other hand, lug nuts are a subtype of wheel nut that secure the wheel with the hub assembly by tightening them on the studs.
Therefore, you should consider this subtle difference between the two while looking for the one from hardware stores.
Can you drive a semi-truck with half the number of lug nuts?
You should never drive a vehicle with half the required lug nuts. Operating with some of them missing poses severe risks and can lead to catastrophic accidents.
They evenly distribute the load and hold the wheels in place. Having half the required numbers means there will be uneven force distribution on the remaining ones, increasing the stress on them.
It also causes additional strain on the semi-truck wheel studs and hub assembly, potentially leading to damage or failure of these components.
It is also a violation of the safety standards, and you will have to pay fine or other punishments in case of any financial or human losses.
What are the symptoms of a missing lug nut on a semi-truck?
It is essential and also a law for semi-truck drivers to be vigilant and inspect the parts responsible for the safety of the truck.
Therefore, they should physically check them at every stop or if they observe any symptoms of a missing, broken, or loose lug nut.
The first symptom you will note is an unusual vibration, especially at higher speeds, because of an imbalance in the wheel assembly.
Some other indications are clicking sounds, increased wear and tear on specific wheel points or other parts like brakes, and misalignment of tires.
You can also feel difficulty in steering the vehicle because of uneven load on the wheels due to missing bolts.
Are there any state laws regarding the number of lug nuts on semi-truck wheels?
According to US Department of Transportation (DOT) safety rules, all the lug nuts of a semi-truck must be secured and tight in their place.
Moreover, every driver should inspect it daily and ensure its tightness. Furthermore, it also prohibits commercial truck drivers from putting a truck into service with a lug nut missing.
Therefore, you should never drive it without properly inspecting that all of these are secure and tight.
Otherwise, during an inspection by the DOT, you can get a challan for violating the safety regulations.
If you are a shift driver, never accept the truck with any studs missing because it is your responsibility if any accident or hazard occurs as a result.