155/90R18 In Inches – Tire Size & Rim Fitment Guide

What tire size is 155/90R18 in Inches?

The 155/90R18 tire has an overall diameter of 29 inches, a section width of 6.1 inches, and can be mounted on 18 inches height of rim. The equivalent tire size in the high flotation system is 29x6.1R18.

	Inches	Millimeters
Tire Diameter	29	736.2
Section Width	6.1	155
Rim Height	18	457
Sidewall Height	5.5	139.5
Circumference	91.1	2312.8

6.1"

29"

91.1"

18"

5.5"

695.8 Revs/Mile

To make it clear, we'll break down each part of the 155/90R18 tire size to know what these numbers represent & how they may affect your tire's performance:

How big is a 155/90R18 tire?

A 155/90R18 tire has a height of 29 inches (736.2 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 155/90R18 tire?

The 155/90R18 tire has a width of 6.1 inches (155 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.

155/90R18 sidewall height

The 155/90R18 has a sidewall height of 5.5 inches (139.5 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 155/90R18 tire?

You can mount the 155/90R18 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.

155/90R18 circumference

The 155/90R18 tire has a circumference of 91.1 inches (2312.8 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.

155/90R18 Revolutions

The 155/90R18 performs 695.8 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 155/90R18

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 155/90R18: