145/85R18 In Inches – Tire Size & Wheel Fitment Guide

What tire size is 145/85R18 in Inches?

The 145/85R18 tire has an overall diameter of 27.7 inches, a section width of 5.7 inches, and can be mounted on 18 inches height of rim. The equivalent tire size in the high flotation system is 27.7x5.7R18.

	Inches	Millimeters
Tire Diameter	27.7	703.7
Section Width	5.7	145
Rim Height	18	457
Sidewall Height	4.9	123.3
Circumference	87	2210.7

5.7"

27.7"

87"

18"

4.9"

728 Revs/Mile

To make it clear, we'll break down each part of the 145/85R18 tire size to know what these numbers represent & how they may affect your tire's performance:

How big is a 145/85R18 tire?

A 145/85R18 tire has a height of 27.7 inches (703.7 mm). This is the measurement from the bottom to the highest point at the top of a tire through its exact center when inflated and unloaded.

How wide is a 145/85R18 tire?

The 145/85R18 tire has a width of 5.7 inches (145 mm). This is the measurement at its thickest point, the distance between the outer sidewall and the inner sidewall’s widest point, also called as tread width or section width.

You can put a slightly narrower or wider tire on a rim as long as it falls within the manufacturer's recommended tire width range.

145/85R18 sidewall height

The 145/85R18 has a sidewall height of 4.9 inches (123.3 mm). It’s measured from the rim to the outer edge of the tire's tread, expressed as a percentage of tire width.

What size rim do I need for 145/85R18 tire?

You can mount the 145/85R18 tire on a rim with a height of 18 inches.

Putting very narrow tires on wide rims or vice versa can result in reduced performance of the tire.

145/85R18 circumference

The 145/85R18 tire has a circumference of 87 inches (2210.7 mm), This is the measurement of the distance the tire travels in one revolution.

The tire circumference is important for your vehicle's overall performance, affecting its speedometer acceleration, accuracy and fuel efficiency.

145/85R18 Revolutions

The 145/85R18 performs 728 revs/mile. Revolutions per mile indicate the number of times a tire rotates while it covers the distance of one mile.

Compatible Tire Sizes for 145/85R18

As a rule, you can replace the tire within a 3% difference in tire diameter (height) of the OEM tire size. However, it should be considered as a general guideline, not a hard and fast rule. Here is a list of compatible tire sizes for 145/85R18: