What to Know about Trailer Tires & Wheels

By Al Henderson, Sr. Engineer, Kenda American Technology Center

Tire and wheel assemblies are an important part of every trailer and are the only trailer component that connects with the road. Understanding what is behind each tire and wheel assembly will help you be sure to have the right one for each situation as well as the ability to answer questions from your customers. After all, a tire that will carry a heavy load for a short distance can be quite different from a tire needed for a long-haul trailer. The information discussed below was featured in NATM’s Tires 101 webinar with Kenda Americana Tire & Wheel. To access the webinar, visit www.NATMShop.com.

Many Components, One Tire

Tires are a complex mixture of many components and layers. The most obvious components are treads and sidewalls but underneath is a complex blend of materials that make each tire perform differently. A single tire could have over 12 different rubber compounds.

• Steel Belts are thin steel wires woven into large sheets and sandwiched between layers of rubber. As the tire flexes in of the tire over a larger area, making it beneficial for wear, handling, and traction.

• Cap plies—Comprised of cords of Nylon, Kevlar, or other fabric, the cap plies provide extra reinforcement to the tire during high speed. They also prevent belts and the carcass from expanding at high speeds due to centrifugal force.

• The tire tread is the most influential part of the tire.

Composed of two rubber components—the tread cap and the tread base.

• The tread cap gets the most wear and tear and is made of a combination of rubber and synthetic materials.

• The tread base adheres the cap to the belt system and helps stabilize the under tread area of the tire.

• Tread design is composed of different rubber blocks, grooves, voids, and sipes—giving the tire its road gripping

power. Road grip is especially important where weather is an issue or the roads are mountainous or winding. Each of the design elements have a specific purpose:

• Circumferential grooves channel out water to prevent hydroplaning

• Lateral grooves provide traction grip on wet surface

• Blocks/Ribs produce stiffness to generate cornering & tractive forces

• Sipes supply additional biting edges for snow traction

• Composed of a special rubber compound, the sidewalls add stiffness between the tread and bead to help transfer torque to the road under acceleration, cornering, and braking. It also protects the carcass plies from abrasion and impact and serves as a shock absorber for the tire to absorb impacts to the tread area.

As mandated by the Department of Transportation (DOT) standards, every tire’s sidewall markings will show how many plies, steel belts, and cap plies are within the tire construction. It’s the unique configuration of the combination of the tires tread patterns, belts and plies, bead design, and sidewalls and shoulders that give each tire type its performance characteristics.

Radial vs Bias

When purchasing tires there’s more to it than just getting the right size tire. You need to take tire construction into account, there aretwo types of trailer tires, radial and bias. The angle of the body plies determines if the tire is “radial” or “bias.”

• A radial tire typically offers a smoother ride, lower noise, better handling and traction, which is why they are exclusively on passenger cars. Radial tires also are often seen on longer distance trailers like RVs, marine, and livestock trailers. Radial tires perform in this way because they have steel belts oriented at a significantly different angle than the 90-degree radial plies. This allows the sidewall and tread to function as two independent features of the tire.

• Bias tires are typically used for shorter distance applications in construction, agriculture or utility. A bias tire consists of multiple rubber plies overlapping each other at a

LET KENDA CARRY YOU.

For over 50 years, Kenda Americana Tire and Wheel has been proudly engineering, manufacturing and assembling world class tires and wheels. You can trust Kenda ATW to carry you.

Visit americanatire.com for sizes, styles and more.

©2021 Kenda Tires. All rights reserved.

30-45-degree angle. The tread and sidewalls are interdependent because all plies have a consistent angle. The overlapped plies form a thick layer that is less flexible which makes it able to carry a heavier load with less trailer sway.

How much air do you need in your tires?

Maintaining proper inflation pressures in your trailer tires is crucial for maintaining even and slow rates of wear. Underinflated tires will result in rapid shoulder wear, while overinflated tires will result in rapid center wear. Overinflated tires can also cause very harsh rides as well as loss of traction.

You should refer to the maximum air pressure on each sidewall as well as work with your supplier’s team to be sure you are recommending the appropriate inflation pressure for each trailer you build. This will provide the most optimum condition for maximizing wear in addition to ensuring good endurance, traction and ride comfort.

Tire Maintenance

To maximize tire life and performance, you need to be sure your customers understand how to take proper care of their tires. The experts at Kenda Americana Tire & Wheel recommend sharing these tips to ensure the tires are ready for the road:

It is crucial customers understand how to care for their tires, as that is literally where the rubber meets the road. • Give your tires a double-take with a visual inspection—

Check that your tires look like they are supposed to–meaning no irregularities, detectable differences from when you stored them, or foreign debris in the tread.

• Put your two cents to the tread test—Your tire tread helps your vehicle grip the road through proper traction and provides a smooth ride. To test your tread depth, take a penny and place Abraham Lincoln’s head upside down and facing you into the shallowest groove on the tire. If Lincoln’s head is visible above the tread, you only have 2/32 of an inch or lesstread depth left. You can also look at your tire for the indicator (wear) bars embedded in the tire at 2/32 of an inch—both may tell you it’s time for new tires.

• Fill them up to recommended pressure—Shifts in temperature and sitting static mean your tires could lose pressure. On average, tires can lose around three percent of air pressure per decrease in temperature of 10 degrees

Celsius. Additionally, even at a constant temperature, tires will lose about three percent inflation pressure per month while sitting around inflated yet not running. More importantly, driving your vehicle with underinflated tires places added pressure on the shoulder of the tire, which can lead to handling issues or uneven wear. Avoid this by checking your air pressure and re-inflating to recommended levels.

• Make sure it’s all systems go!—Just like with a car, checking your vehicle’s systems before major towing should be standard practice. For your trailer, be sure to connect to the tow vehicle power and check all of the exterior lights— running lights, headlights, accessory lights, brake lights, etc.

Also, inspect your hitch components and 12-volt electrical plugs for your tow vehicle.

Remember, this is really where the rubber hits the road and as the trailers only contact with the road surface you want to be sure to utilize the appropriate tire to best transfer driver inputs such as braking, accelerating, and turning. Using this information on tire components, tire types and maintenance tips will help ensure you are not only using the correct tires for each trailer you build but sharing the most accurate insights and tips with your customers. This ultimately improves their satisfaction with your trailer and can lead to safer roadways. Something we all can benefit from.