/55 series tire aspect ratio

What does /55 mean in a tire size?

A /55 aspect ratio means the tire sidewall height is 55% of the section width. For a 205/55R16 tire, the sidewall is 112.75mm tall. Common 55-series sizes span multiple rim diameters.

FAQ

What does /55 mean in a tire size?
A /55 aspect ratio means the tire sidewall height is 55% of the section width. For a 205/55R16 tire, the sidewall is 112.75mm tall. Common 55-series sizes span multiple rim diameters.
What should I verify before using this information?
Use TireFitLab values as a sizing reference, then verify the vehicle handbook, tire placard, rim compatibility, load rating, and physical clearance before fitting.

16 popular /55 series sizes

Full aspect ratio guide · Tire section width guide · Tire size calculator

Seasonal check

Planning a long summer drive?

Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.

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Last reviewed: 2026-06-28
What changed
  • Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.