What is the diameter difference between 185/65R14 and 205/55R16?

185/65R14 has an overall diameter of 23.47 inches (596 mm). 205/55R16 is 24.88 inches (632 mm). That's a 1.41 inch (36 mm) difference — 205/55R16 is taller.

Will 205/55R16 cause speedometer error on a car fitted with 185/65R14?

Swapping 185/65R14 for 205/55R16 produces a speedometer error of about 6%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 63.6 mph. Anything under 3% is usually acceptable without recalibration.

How many revolutions per mile does each size do?

185/65R14 turns 859 revs per mile. 205/55R16 turns 811 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.

What's the sidewall height difference?

185/65R14 has a sidewall of 120 mm (4.73 in). 205/55R16 sidewall is 113 mm (4.44 in). Lower-profile sidewalls give sharper steering response but less bump compliance.

Is 205/55R16 a safe plus-size upgrade from 185/65R14?

A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 6%. This swap is outside the typical ±3% safe range and may require speedometer recalibration or affect ABS / traction control behaviour.

Tire size comparison

185/65R14 vs 205/55R16

Overall diameter, sidewall, revs per mile, and speedometer error — 205/55R16 is the taller tire, with a 6% speedo delta when swapping.

185/65R14

23.47in

596 mm overall diameter

205/55R16

24.88in

632 mm overall diameter

Diameter Δ

1.41 in

Speedo error

185/65R14 revs/mi

859

205/55R16 revs/mi

811

Outside the typical ±3% safe plus-size band — you may want speedometer recalibration, and this change can affect ABS or traction control behaviour.

Full spec

Side by side

Metric	185/65R14	205/55R16
Section width	185 mm	205 mm
Aspect ratio	65	55
Wheel diameter	14″	16″
Sidewall height	120 mm	113 mm
Overall diameter	23.47 in (596 mm)	24.88 in (632 mm)
Circumference	73.73 in	78.16 in
Revolutions / mile	859	811

Other comparisons for these sizes

175/65R14 vs 185/65R14 185/65R14 vs 195/60R15 185/65R14 vs 185/60R15 195/60R15 vs 205/55R16 205/55R16 vs 215/50R17 205/55R16 vs 205/50R17 205/55R16 vs 225/45R18 205/55R16 vs 205/60R16

FAQ

Frequently asked

What is the diameter difference between 185/65R14 and 205/55R16?: 185/65R14 has an overall diameter of 23.47 inches (596 mm). 205/55R16 is 24.88 inches (632 mm). That's a 1.41 inch (36 mm) difference — 205/55R16 is taller.
Will 205/55R16 cause speedometer error on a car fitted with 185/65R14?: Swapping 185/65R14 for 205/55R16 produces a speedometer error of about 6%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 63.6 mph. Anything under 3% is usually acceptable without recalibration.
How many revolutions per mile does each size do?: 185/65R14 turns 859 revs per mile. 205/55R16 turns 811 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.
What's the sidewall height difference?: 185/65R14 has a sidewall of 120 mm (4.73 in). 205/55R16 sidewall is 113 mm (4.44 in). Lower-profile sidewalls give sharper steering response but less bump compliance.
Is 205/55R16 a safe plus-size upgrade from 185/65R14?: A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 6%. This swap is outside the typical ±3% safe range and may require speedometer recalibration or affect ABS / traction control behaviour.