All 305/40R21 tires

305/40R21 is also written 305 40 R21, 305/40 R21, 305 40 21 or 3054021. 305 is the tread width in millimetres, 40 the aspect ratio (sidewall height as a percentage of the width), R stands for radial construction, and 21 the rim diameter in inches.

A 305/40R21 tire is about 777.4 mm (30.6 in) tall, with a sidewall of 122.0 mm.

An equivalent size is a tire whose overall diameter stays within 3% of 305/40R21, so the speedometer, gearing and wheel-well clearance stay close to what the vehicle was designed for. People look for one when 305/40R21 is scarce or expensive, or when they want a different width or rim size. An equivalent size is not an automatic swap, and we do not guarantee that it fits your vehicle: check the rim width range, make sure the load index is at least the original, and allow for possible rubbing. Add your car above and rely on the “Fits on your vehicle” label shown on each product to confirm the fit.

• 245/55R20+0.01% · 20"chevron_right
• 275/40R22+0.18% · 22"chevron_right
• 315/35R22+0.24% · 22"chevron_right
• 275/45R21+0.45%chevron_right
• 295/45R20-0.5% · 20"chevron_right
• 265/50R20-0.57% · 20"chevron_right

Sidewall 122.0 mm, overall diameter 777.4 mm (30.6 in), circumference 2442.3 mm, 409.5 revolutions per km.

Read the full guide

305/40R21 tires start at $694.29 at PMC Tire. We list 3 tires in this dimension.

It depends on the exact vehicle and trim. Add your car above to check which tires in this size fit it.

In Quebec, winter tires are mandatory from December 1 to March 15, and only tires with the three-peak mountain snowflake symbol qualify. Our guide explains how to choose. Read the full guide

We carry 305/40R21 tires from 2 brands, including Pirelli, Michelin.