185/55R15
Overall diameter 584.5 mm
185/55R15 — 584.5 mm tall, and what it swaps with
185/55R15 is 185 mm wide with a 55% sidewall on a 15-inch wheel. That sidewall is 101.75 mm, so the tyre stands 584.5 mm tall and turns 544.6 times per kilometre.
- Section width
- 185 mm
- Aspect ratio
- 55 %
- Wheel size
- 15 in (381 mm)
- Sidewall height
- 101.75 mm
- Overall diameter
- 584.5 mm (23.01 in)
- Circumference
- 1836.3 mm
- Turns per km
- 544.6
Sizes you can swap to
Only sizes whose overall diameter stays within 3% are listed. A different diameter covers a different distance per turn, and that gap becomes speedometer error.
175/65R14583.1 mm · -0.24% you go slower165/70R14586.6 mm · +0.36% you go faster195/45R16581.9 mm · -0.44% you go slower185/70R13589.2 mm · +0.8% you go faster195/60R14589.6 mm · +0.87% you go faster205/45R16590.9 mm · +1.09% you go faster185/60R14577.6 mm · -1.18% you go slower175/70R13575.2 mm · -1.59% you go slower195/55R15595.5 mm · +1.88% you go faster205/40R17595.8 mm · +1.93% you go faster185/65R14596.1 mm · +1.98% you go faster175/70R14600.6 mm · +2.75% you go faster
Same profile, different width
Other sizes for this wheel
How the code reads
The 205 is millimetres, the 55 is a percentage of that width, and only the 16 is inches. The R stands for radial construction.
How to read this
- The first three digits are the width in mm, the middle two are the aspect ratio in percent, the last two the wheel in inches.
- Sidewall height = width × aspect ÷ 100. For 205/55 that is 112.75 mm.
- Overall diameter = wheel diameter + twice the sidewall. A 16-inch wheel is 406.4 mm.
- Once the diameter shifts by more than 3%, the speedometer and odometer drift by the same amount.
Frequently asked questions
Q. What is the overall diameter of 185/55R15?
584.5 mm — the 381 mm wheel plus the 101.75 mm sidewall at top and bottom.
Q. How many turns per kilometre does 185/55R15 make?
Its circumference is 1836.3 mm, so 544.6 turns.
Q. What can I swap it for?
12 sizes stay within 3% of its diameter — the closest is 175/65R14 at 583.1 mm.
Q. Why is the sidewall 101.75 mm?
Because it is 55% of the 185 mm width. The aspect ratio is a proportion of the width, not a length.