Difference Between Radial and Bias Tyres

If you have heard of radial and bias tyres or seen them yourself, you probably think that they are quite similar. And they are. However, there are several differences which are very important – shared in our article below.

Tyres are more than just big, rubber donuts. In an era like today, there are so many different sizes, shapes, forms, materials and models, that it is hard to differentiate between each of them. Because of this, many vehicle owners are unsure which is the best tyre for their needs. When it comes to tyres for trailers, there is a big debate over radial and bias tyres as one of the most popular and common options.

Trailer tyres have evolved a lot over the past few decades. However, even with this evolution, some owners of trailer vehicles still don’t know whether radial or a bias tyres are better for their needs.

At Tyres Online, we get a lot of questions about the difference between a radial tyre and a bias ply from our customers. This is why today, we are listing all of the good and bad things about both constructions, and the best way to use each tyre.

The Difference Lies In The Construction

What most don’t know is that the terms “radial” and “bias ply” are used to describe the internal construction of a tyre. Therefore, the difference between both models is small, but still has a significant impact on the performance of the tyre and several other features.

If you know more about tyres than an average person, you probably know that they are made by stacking layers of rubber and reinforcing fabric. Once upon a time, cotton was used to reinforce tyres, but that material has changed with nylon, polyester, rayon, fiberglass and even Kevlar being put to use for strength and support. Each of these layers is called a “ply”. So, the difference between radial and bias ply tyres is the way that the plies are laid in relation to each other.

Radial (left) vs. Bias Ply (right) tyre construction. (Source: Reddit.com)

How To Check If I Have Bias Ply Or Radial Tyres?

Your trailer or RV probably has either of these models. The best way to check whether it is outfitted with bias ply or radial tyres is by looking on the sidewall. Just below the tyre size, you will be able to find the word ‘radial’ or ‘bias’. If it says ‘radial’ you should know that you have the more expensive and more robust tyre specification. However, there are many different aspects in both of these models – explained below.

Let’s take a look at both of the constructions in detail.

Bias Ply Tyre Construction

• Bias ply tyres are made with reinforcing cord which is laid out diagonlly (typically 30 or 40 degrees) from the direction of travel from each bead to bead.
• Each additional ply has reinforcing cords that are laid at an opposing angle to the ply beneath it. This creates a criss-cross pattern.
• Most bias ply tyres are 4, which means they have 4 layers of reinforcing fabric cords
• 6 ply, 8 ply and 10 ply options are available for heavier vehicles only.
• The sidewall and the tread are both supported by the same reinforcing piles, giving the tyre some unique characteristics.

Radial Tyre Construction

• In radial tyres, the reinforcing cords are laid at a 90 degree angle from the direction of travel from bead to bead
• Each additional ply is laid in the same direction as the one located underneath it, making all the reinforcing cords to run in parallel to each other.
• The reinforcing belts are added between the radial plies and the tread (here, belts are made from woven strands of steel, nylon, Kevlar and other materials).
• More rubber is applied over the belts to create the tread.
• The sidewall and tread are two independent parts of the tyre.
• Since the technology progressed a lot from the early 1970s, radial is known to have many benefits over bias ply tyres.

So, Which To Choose Between Radial And Bias Ply Tyres?

As we already mentioned above, the main difference in both tyre models lies in the belts of tyre and their construction. Radial trailer tyres use steel belts which are laid at a 90 degree angle of the tread center line. In bias ply tyres, there are nylon belts of the tyre constructed at a 30-45 degree angle of the tread center line.

Therefore, the benefits of choosing a radial trailer tyre are cooler running, steel belts (tougher overall construction), longer tread life and a wider footprint. Their disadvantages are the ride quality, potential sidewall damage and harder tread which can result in greater tyre noise.

The benefits of choosing bias ply tyres for trailers include stronger and tougher sidewalls, straight rolling and less expensive prices. The down points for this model include the fact that they wear out faster due to high traction, their high rolling resistance which may lead to worse fuel economy, and the rollover effect that causes loss of traction while cornering.

If you are in doubt about which to choose for your trailer, you should know that radial tyres are better for longer trips and regular use of your triler. They are tough, have a longer lifespan and a wider footprint which can sometimes make them safer.

Similarly, bias ply tyres are better for short trips, as well as tandem axle trailers and/or vehicles which are not used frequently. 

Learning More About Trailer Tyres

As the owner of a trailer, it is important for you to ask questions and look for information about tyres online. Typically, trailer tyres need to be replaced before the tread is fully exhausted.

In that manner, the Department of Transportation (DOT) recommends replacing all trailer tyres at least once in every six years. Most importantly, this recommendation is based on years rather than mileage, which is something to be aware of.

Now, while we know that some trailer tyres are more robust and built for higher mileage, trailer tyres are not that mobile which is why the DOT recommends replacing them more often. After all, you don’t drive your trailer everywhere you go and there is a reason why the general rule of thumb for a tyre in this caliber is around 25,000 miles.

Final Verdict

In the end, buying a trailer is a big investment, and one that comes with many details in mind. Choosing the right trailer tyres is one of them. If you want to use your trailer for longer trips and use it more regularly, spending a bit more on a radial trailer tyres can help you take advantage of its longer tread life.

But if you see your trailer being parked more than it is driven, you don’t have to overspend and a bias ply tyre solution can be perfect for your needs. At Tyres Online, we offer both Radial and Bias Ply trailer tyres in our online store and at some of the best prices online.
For more information on this and a chance to shop the best tyres online in UAE, visit this link!