What’s special about the new R280 steer radial?

The R280 provides a real answer for fleets who want extended steer tire mileage while getting full use of their casings for drive tire retreads.

How does the R280 extend tire mileage?

The R280 has a full 18/32" tread depth, ideal for steer tires, combined with a wider-than-normal tread. It spreads load and wear forces over a wider area, for slower overall wear.

What about irregular wear resistance?

The R280 combines its wide tread with patented, proven features that promote even tread wear. That’s important, because the single most important reason steer tires are removed from service is irregular wear, not wearout.

What kind of irregular wear-fighting features?

First, the R280 has Bridgestone’s proven Defense Groove™ design. That’s the tiny groove you see near each shoulder.

1. The R280 incorporates Bridgestone's Defense Groove™ technology, a proven technique for preventing the start and spread of irregular shoulder wear. 2. Just as the Defense Groove design protects the shoulder ribs, so the Equalizer rib structures help prevent irregular wear on main tread ribs

What does the Defense Groove design do?

Invented by Bridgestone, this small groove creates a small rib that wears away faster than the main rib beside it, attracting irregular wear forces to itself and away from the main rib.

By sacrificing itself, the Defense Rib helps protect the main rib against shoulder step-down wear.

Does the R280 have other features to promote even wear?

Take a look at what are called Equalizer Rib™ structures. These are in the first main grooves, near the shoulder rib.

Notice that as in the shoulders, you have a small rib next to a main tread rib. And, as you might expect, these Equalizer Rib structures attract irregular wear forces to themselves, like lightning rods.

When tires in a dual assembly have unequal diameters, the smaller tire is dragged by the larger to cover the same distance with each revolution, accelerating wear on the smaller.

Why is that?

Remember what happens in dual assemblies with mismatched diameters? Because the tires differ in circumference, the smaller tire gets “dragged” along, to cover the same amount of pavement as the larger tire.

That’s what happens with Equalizer Rib structures. They’re “stepped down” from the main ribs beside them, so like the smaller tire in a mismatched dual pair, they wear away faster.

As they do, they attract irregular wear forces to themselves, and away from the main ribs. This is an exclusive, patented Bridgestone feature for preventing irregular wear.

The ribs have slits across them.

All three of the central ribs of the R280 have angled slits or “sipes.” Sipes are a proven way to improve wet traction.

As the tire rolls, the sipes open slightly as they contact wet pavement. Water is drawn into the sipe, drying the road a bit. At the same time, the edge of the tread element slices through the water to make contact with the road. That’s how sipes increase wet traction.

But even these sipes are special.

How is that?

Each of the tread elements of the R280 is linked to the ones adjacent to it by carefully engineered “tie bars.”

By linking each element to the others, Bridgestone engineers are able to stabilize them, reducing tread squirm, a major cause of irregular wear.

Each R280 tread element is linked to it's neighbors with "tie bars," to stabilize the elements and prevent squirm that could cause irregular wear.

What do the notches do?

Those are called “stress relief sipes.” Their job is to reduce tread stress as the tire rolls through its footprint.

Notches along the edges of ribs release footprint stresses that can initiate and spread irregular rib edge wear.

How do they do that?

A tire tread is circular. But when it’s pressed against the pavement, it flattens out. The rubber at the very outside of the rib is compressed into itself then released as the tread exits the footprint.

This constant squeezing and expanding causes stresses at tread edges. For woodworkers, a common technique is to notch the edge of a strip of wood that has to be fitted around a curve. The principle is similar here.

The notches relieve stresses in the ribs as they roll through the footprint. Less stress means less tendency for irregular rib edge wear to start and spread.

Special platforms at the bottom of the tread grooves help prevent damaging stones from being captured.

How does the R280 enhance retreadability?

On either side of the center rib, there are rows of tiny platforms. These flex with every movement of the tread.
Their job is to prevent stones from becoming lodged in the tread grooves. When a stone gets stuck in a groove, it tends to be driven deeper and deeper into the tread.

As the tread wears, stones can actually drill through the bottom of the grooves, penetrating the undertread layer and even the belts.

The result can be belt damage, rust, or both. Both can diminish retreadability.
As these groove bottom platforms flex and move, they tend to dislodge stones, preventing them from getting a foothold.

Just as woodworkers notch the edge of a piece of wood to help it bend more easily, the rib edge notches of the R280 help reduce footprint stresses when its ribs flatten against the road.

How else is retreadability enhanced?

Fleets are often disappointed when they retread steer tires for use on drive axles. Many steer tires have a fairly narrow tread, and that limits the width of the drive tread that can be put on them.

Drivers tend to look at these “skinny retreads” and question whether they’re going to provide the pulling power they need.

To counter this, the R280 features a wide tread base, which when buffed, can accept a full width drive cap. The result is wider drive retreads, which can reduce driver complaints.

A free brochure on the R280 radial is available from your dealer, your Bridgestone representative, or by requesting one here.

When will the R280 be available?

The R280 is available now in standard and low profile sizes for 22.5 and 24.5-inch wheels. If you’re looking for long, even steer tire wear – together with great retreadability – the R280 could be just the tire for you. Ask your dealer or Bridgestone representative for a free brochure.