Tire Ratios

Front

What does the tire size P255/55R18 represent?

Back

P255/55R18 indicates a tire with a section width of 255 mm, an aspect ratio of 55 (height is 55% of the width), and it fits on an 18-inch rim.

Front

How do you calculate the diameter of a tire given its size P255/55R18?

Back

Diameter = Rim Diameter + 2 * (Section Width * Aspect Ratio) = 18 + 2 * (255 * 0.55 / 25.4) = 29.04 inches.

Front

In the tire size 245/70R16, which number must remain the same when changing to bigger tires but keeping the same rims?

Back

The number 16 must remain the same, as it represents the rim diameter in inches.

Front

What does the number 205 represent in the tire size P205/65R16?

Back

The number 205 represents the section width of the tire in millimeters.

Front

What is the aspect ratio in tire sizing?

Back

The aspect ratio is the ratio of the height of the tire's sidewall to its section width, expressed as a percentage.

Front

How do you calculate the circumference of a tire with size 275/70R18?

Back

Circumference = Diameter * π. First, calculate the diameter, then multiply by π (approximately 3.14) to find the circumference.

Front

What is the formula to find the diameter of a tire from its size?

Back

Diameter = Rim Diameter + 2 * (Section Width * Aspect Ratio / 25.4).

Front

What does the 'R' in tire sizing (e.g., P255/55R18) stand for?

Back

The 'R' stands for 'Radial', indicating the construction type of the tire.

Front

What is the significance of the tire's section width?

Back

The section width is the width of the tire from sidewall to sidewall, measured in millimeters, and affects the tire's grip and handling.

Front

What is the relationship between tire height and width called?

Back

The relationship is called the aspect ratio.