225/55R18 Tire Size Specifications & Compatible Vehicles

Overall Diameter

704.7 mm

Section Width

225 mm

Sidewall Height

123.8 mm

Circumference

2213.9 mm

Revs/Mile

727

Rim Diameter

18"

Inch Equivalent

27.7x8.9R18

Rim Width (ETRTO)

6.5" – 8.5"

Compatible Vehicles

The following vehicles use 225/55R18 tires from the factory:

2025 Audi A6 Premium 45 TFSI 2024 Audi A6 Premium 45 TFSI 2023 Audi A6 Premium 45 TFSI 2022 Audi A6 Premium 45 TFSI 2021 Audi A6 Premium 45 TFSI 2020 Audi A6 Premium 45 TFSI 2025 Buick Encore GX Sport Touring 2025 Buick Encore GX Avenir 2024 Buick Encore GX Sport Touring 2024 Buick Encore GX Avenir 2023 Buick Encore GX Avenir 2022 Buick Encore GX Essence 2021 Buick Encore GX Essence 2020 Buick Encore GX Essence 2021 Hyundai Tucson Sport/Limited/Ultimate 2020 Hyundai Tucson Sport/Limited/Ultimate 2021 Mitsubishi Outlander SEL 2020 Mitsubishi Outlander SEL 2025 Mitsubishi Eclipse Cross SEL 2024 Mitsubishi Eclipse Cross SEL 2023 Mitsubishi Eclipse Cross SEL 2022 Mitsubishi Eclipse Cross SEL 2021 Mitsubishi Eclipse Cross ES 2021 Mitsubishi Eclipse Cross SE 2020 Mitsubishi Eclipse Cross ES 2020 Mitsubishi Eclipse Cross SE 2025 Subaru Crosstrek Sport/Limited 2024 Subaru Crosstrek Sport/Limited 2023 Subaru Crosstrek Sport/Limited 2022 Subaru Crosstrek Sport/Limited 2021 Subaru Crosstrek Sport/Limited 2020 Subaru Crosstrek Limited 2025 Subaru Forester Sport/Limited/Touring 2024 Subaru Forester Sport/Limited/Touring 2023 Subaru Forester Sport/Limited/Touring 2022 Subaru Forester Sport/Limited/Touring 2021 Subaru Forester Sport/Limited/Touring 2020 Subaru Forester Sport/Limited/Touring

Alternative Tire Sizes

These tire sizes are within 3% overall diameter of 225/55R18 and may be used as replacements:

165/75R18 Safe 0.0% diff 275/45R18 Safe 0.0% diff 195/70R17 Safe 0.0% diff 185/60R19 Safe 0.0% diff 155/80R18 Safe 0.1% diff 245/40R20 Safe 0.1% diff 175/85R16 Safe 0.1% diff 165/60R20 Safe 0.2% diff 205/60R18 Safe 0.2% diff 305/45R17 Safe 0.2% diff 245/45R19 Safe 0.2% diff 315/35R19 Safe 0.2% diff

Popular Comparisons

See how 225/55R18 compares to other common tire sizes:

225/55R18 vs 235/55R19 Crossover size upgrade 215/60R17 vs 225/55R18 Crossover rim upgrade 225/55R18 vs 235/55R18 Midsize SUV width upgrade 225/55R18 vs 245/50R19 SUV plus-one wider upgrade 215/55R18 vs 225/55R18 EV crossover width upgrade

Understanding 225/55R18

The tire size 225/55R18 means the tire has a section width of 225mm, an aspect ratio of 55% (the sidewall height is 55% of the width), and fits a 18-inch rim.

Sidewall Height = 225 x 0.55 = 123.8 mm
Overall Diameter = (123.8 x 2) + (18 x 25.4) = 704.7 mm
Circumference = 704.7 x π = 2213.9 mm

Frequently Asked Questions

What vehicles use 225/55R18 tires? ▼

The 225/55R18 tire size is used on 38 vehicle trims including the 2025 Audi A6, 2024 Audi A6, 2023 Audi A6 and 35 more.

What is the diameter of a 225/55R18 tire? ▼

A 225/55R18 tire has an overall diameter of 704.7mm (27.7 inches). The sidewall height is 123.8mm, and the total circumference is 2214mm.

What rim width do I need for 225/55R18 tires? ▼

For 225/55R18 tires, the ETRTO recommended rim width is 7.5". The acceptable range is 6.5" minimum to 8.5" maximum. Using a rim outside this range can cause improper bead seating and unsafe handling.

Can I replace 225/55R18 with a different size? ▼

Yes, as long as the replacement tire overall diameter is within 3% of the 225/55R18 704.7mm diameter. Compatible alternatives include 165/75R18, 275/45R18, 195/70R17. Use our Tire Size Calculator to compare any two sizes.