Technical Dictionary

R-Compounding

A racing-derived compound optimized for on-track performance and designed for maximum dry grip and repeated heat cycles.

Radial XSE® Technology

A revolutionary technology that utilizes silica in the rubber compound to enhance a tyre’s wet traction, snow traction, and rolling resistance.

Revolutions Per Mile (RPM)

Also called rpm. Measured number of revolutions for a tyre traveling one mile. This can vary with speed, load, and inflation pressure.

Ribs

A pattern of tread features aligned around the circumference of a tyre. There are usually multiple ribs across the tread area of a tyre.

Ride height

The distance from the ground to a fixed reference point (differs by automaker) on the vehicle’s body. This dimension can used to measure the amount of suspension travel or the height of the body from the ground.

Rim diameter

The diameter of the rim bead seats supporting the tyre.

Rim Drop

Also called drop center, a change (drop) in the rim profile between the rim flanges in which the bead area of a tyre is placed during the mounting process. This allows the tyre to be mounted on the rim.

Rim flange

Surface of the rim of the wheel that contacts the side of the tyre bead.

Rolling circumference

The linear distance traveled by a tyre in one revolution (its circumference). This can vary with load and inflation. Rolling circumference can be calculated as follows: 63,360 divided by revolutions per mile = rolling circumference in inches.

Rolling resistance

The force required to keep a tyre moving at a uniform speed. The lower the rolling resistance, the less energy needed to keep a tyre moving.

Rotation

The changing of tyres from front to rear or from side to side on a vehicle according to a set pattern; provides even treadwear. Rotating your tyres on a regular basis (every 6,000-8,000 miles) is a simple way to add miles to their life. See your tyre warranty for more information on recommended rotation.

Rubber compound

A combination of raw materials blended according to carefully developed procedures. The rubber compound is specially adapted to the performance required of each type of tyre.

Runout

The amount a wheel moves in and out, away from its true center as it is rotated. If runout is excessive, the wheel can be seen to wobble as it rotates.