Bias Vs. Radial

May 24th 2019

Bias Vs. Radial

Bias Vs. Radial

May 24th 2019

If you’ve been keeping up with our blog, by now you know there’s 2 main types of tire construction: bias and radial. We’ve talked about both of these individually, but now it’s time to bring that knowledge together. Is one better than the other? Which should you use? Why can’t you just use both?

Before we get started let’s briefly review some of the basics:

  • What are plies? Plies are what make up part of the internal structure of a tire. They’re usually some kind of textile material (like nylon or kevlar) fused with rubber compounds to form a sheet. These ply sheets are then layered to form the structure of the tire.
  • What’s Bias? Bias means the plies are laid on a bias, or diagonal, from the center of the tire. So each ply is laid on a diagonal from one bead to the other, criss crossing each other, usually at a 30 to 40 degree angle to the center line.
  • What’s Radial? Radial means the plies are laid straight across from one bead to the other, and they don’t cross. They’re usually at a 90 degree angle to the center line, or perpendicular.

So What’s the Difference?

You may think the only real difference between these constructions is age. You see bias tires were the original style of making tires up until the 1970s, when radials finally took over, so it’s understandable to think this. However, bias tires are still around today, and they do have their benefits.

In reality, because of their different constructions, each construction will function and perform slightly differently. This is actually why bias tires are still around, because there are pros and cons to each. For example, bias tires tend to have thicker sidewalls and a smaller footprint due to the way the plies are laid out. This makes them super durable and great for heavier loads, as the sidewalls are thicker. However, because the plies overlap, whenever the sidewalls flex, so does the tread, making the footprint deform ever so slightly. Radials, on the other hand, have thinner sidewalls and a wider footprint. Since the way the plies are laid out lets the sidewalls flex independently of the tread area, they tend to last longer. However they’re not as durable or able to take heavy loads.

So Which One’s Better?

Well, neither. As I said, the each have their pros and cons, so really it depends on your vehicle, what you’re doing, and what you need the tires to do.

Bias Tires Are Better For:

  • Short Trips-They’re pretty heavy duty, but their thicker construction means they don’t handle heat as well. So short trips are better.
  • Rough Terrains- If you have an ATV/UTV you might consider bias tires for their ruggedness. They’re less prone to punctures and they’re easily able to flex over uneven terrain
  • Trailers/Heavy Loads-Not only are the sidewalls thick and able to withstand the load, they are also great for towing as the construction makes them roll straight. The stiffer sidewall also means less sway and bounce.
  • Touring Motorcycles-The thick sidewalls aren’t great for racing or sport motorcycles, but if you’ve got a touring bike it actually makes for a comfortable and sturdy ride.
  • Lower Speeds- The bias construction means they do have a higher rolling resistance and you’ll get less control in higher speeds, so these are better for lower speed, around town sort of driving.

Radial Tires Are Best For:

  • Long Trips- Radial tires are thinner, and as such they don’t generate as much heat, making them great for long drives.
  • Performance or Racing- The sidewalls are more flexible without deforming the footprint, which is great for cornering, maneuvering, and traction. The heat tolerance is excellent for high speeds as well.
  • Light Trucks- As they often have steel belts, these tires can have a pretty sturdy overall construction. Provided they have the appropriate load rating, this makes them great for light trucks that need to carry moderate loads and do regular driving.
  • Highway Driving- Because they’re heat tolerant with flexible sidewalls and a sturdy footprint, they’re ideal for travelling at higher speeds over longer periods of time.
  • Regularly Used Trailers- As long as they’re ST rated, radial tires would be a better option for trailers that are used regularly or on long or highway trips. This is again due to their heat tolerance, but they’re also less prone to developing flat sparts when parked for an extended period.

Why Can’t You Just Use Both?

Just like LT and Passenger tires, bias and radial tires can’t be mixed on the same vehicle. Also like Passenger and LT tires, this is due to the differences in their construction.

As I said above, their construction differences make them perform differently in certain situations. A bias tires sidewalls are thicker and their flex directly affects the tread area and the footprint. This can make them more prone to slippage, not to mention the thickness leads to more heat buildup. Meanwhile, your radial tires have sidewalls that function independently from the tread area or footprint, making them excellent for traction, maneuvering and long drives. This independent function, however, means the footprint is sturdier, and therefore doesn’t flex around large rocks and holes, so these tires are not great for rougher terrain.

Now imagine having both of these tires on your vehicle. You’re driving down the highway and suddenly your bias tires overheat and fail. Or you’re driving on a dirt road and you hit a big rock and your radial tires sidewall pops. Or maybe nothing catastrophic happens and you just find it awkward and harder to control your car around corners.

The bottom line is this: Different construction means a different ride. Don’t mix them.

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