The new M725 drive radial features a 30/32” ultra-deep tread, along with the open shoulder design favored by LTL fleets and others running single drive axles.

How does driver acceptance fit in?

Even though extensive testing shows that closed shoulder drive tires, like the M726, produce outstanding wet traction, many drivers believe open-shoulder designs can provide more traction on soft surfaces, like snow.

They look for aggressive block designs and open shoulders, especially for single drive axle tractors, believing these have better traction.

And is that true?

Single axle tractors often have engines just as big as tandem drive tractors. They can put enormous torque into their axles, and can spin the tires, especially on soft surfaces.

The tandem axle rig generates traction by putting twice as many tires in contact with the ground. The single axle rig has fewer tires on the ground, and needs more traction from each.

With an aggressive tread pattern and open shoulders that accentuate its ability to dig in and hold, a tire like the M725 may provide superior traction on single drive axles.

Single drive axle tractors put half as many tires on the road as tandem drive axles do, so each of those tires needs more aggressive traction, especially on soft surfaces.

Are there other problems with single axle tractors?

The high torque of single axle tractors often makes the tires subject to both rapid and irregular wear.

Why is that?

You’re pulling the same amount of weight, but with half as many tires as on a tandem rig. The stress on the tire treads is enormous.

And, the deeper the tread, the more the tread blocks tend to deform and squirm. So, making a 30/32”-deep tread for single drive axles presents special challenges.

Staggered block patterns on selected M725 models incorporate tie bars and buttressed shapes to give them resistance to side forces and squirm that can iniate irregular wear.

What is Bridgestone’s answer?

Part of it is to link tread blocks, on certain sizes, with “tie bars” that make multiple blocks help each other resist high torque and scrub.

And, the blocks in M725 radials also have a buttressed design, with the base of the block wider than the top, to provide additional strength.

And how does the M725 resist irregular wear?

With block-type tires, a common irregular wear condition is what is called “heel and toe” wear. As the tire turns, and each block comes in contact with the pavement, the edge that touches first, the “heel,” is compressed and pushed in the direction of travel.

The other edge, the “toe,” is distorted by the force of the weight on it – in the same direction. As the tire rolls through its footprint, eventually only the very edge of the tread block is in contact with the pavement.

At this point, the edge of the tread can “snap” and “drag” as it loses contact with the road. This creates more wear on the trailing edge of the block than on the leading edge, a phenomenon called “heel and toe wear.”

With typical ultra-deep drive axle radial designs, as each tread block leaves the footprint, its edge tends to “snap” and “drag,” causing extra wear on that side of the block.

How does the M725 fight heel and toe wear?

On some models, by changing the shape of the block to reduce the “snap and drag” effect. Each block, instead of being flat, has a rounded shape. This Dome Block™ design is a patented,exclusive Bridgestone feature.

What it does is make the dome-shaped block, when loaded, more closely resemble a flat-shaped block when unloaded.

The result is that as the block rolls through contact with the road, there’s less block distortion and less tendency to snap and drag, for less heel and toe wear.

Bridgestone’s patented Dome Block™ design fights tendency of block edges to drag against the pavement, for even wear and reduced need for rotation.

What’s the benefit of that?

If you find you’re frequently rotating drive tires to equalize heel and toe wear, the M725 may reduce or even eliminate the need for rotation, a savings in time and money, and in reduced driver complaints.

Can we expect long life from the M725?

You certainly can. Besides having a full 30/32”-deep tread, as deep as any line haul drive radial on the market, the M725 also incorporates other features that provide long life, outstanding traction and superior retreadability.

For example, notice how the bottoms of the tread grooves are covered with hundreds of tiny platforms. These button-like structures flex and move as the tire rolls through its footprint, and push against gravel and stones, preventing them from being retained by the tread.

Thousands of tiny platforms at the bottom of tread grooves fight stone retention that can damage casings and diminish retreadability.

How does that help?

Retained stones get pushed into the grooves as the tire wears, and can eventually bruise or even penetrate the steel cords, damaging them and exposing them to air, making them susceptible to rust. Both rust and cord bruises can diminish retreadability.

How does the M725 do on wet traction?

Very well. The M725 tread design provides thousands of sharp block edges that slice through water and road films for a solid grip.

In addition, hundreds of sipes provide extra traction edges and paths to draw water out of the footprint.

What sizes are available?

The new M725 radial is available in both 295/75R22.5 and 285/75R24.5 low profile sizes, as well as in 11R22.5 and 11R24.5 standard profile sizes, all in the 14-ply, G-load range.

The M725 is available now from your Bridgestone dealer, so if you use single drive axles and straight trucks, finally, there’s an ultra-deep drive tire made specially for you.