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Tire Size Comparison

185/65R15 vs 215/55R16

Switching from 185/65R15 to 215/55R16 changes overall diameter by +3.44% (24.47 in → 25.31 in).

+3.44%Borderline — noticeable speedometer/odometer error

Speedometer error

With a speedometer calibrated to 185/65R15, fitting 215/55R16 makes it read as follows:

Speedo showsTrue speedSpeedo showsTrue speed
40 km/h41.4 km/h25 mph26 mph
60 km/h62.1 km/h37 mph39 mph
80 km/h82.8 km/h50 mph51 mph
100 km/h103.4 km/h62 mph64 mph
120 km/h124.1 km/h75 mph77 mph

Full comparison

185/65R15
Overall diameter621.5 mm · 24.47 in
Section width185 mm · 7.28 in
Sidewall height120.3 mm · 4.73 in
Circumference1952.5 mm · 76.9 in
Revolutions per mile824
Revolutions per km512
215/55R16
Overall diameter642.9 mm · 25.31 in
Section width215 mm · 8.46 in
Sidewall height118.3 mm · 4.66 in
Circumference2019.7 mm · 79.5 in
Revolutions per mile797
Revolutions per km495
Original tire
New tire
+3.44%Borderline — noticeable speedometer/odometer error
24.525.3
Original
Overall diameter621.5 mm · 24.47 in
Sidewall height120.3 mm
Circumference1,952.5 mm
Revolutions / mile824.2
New
Overall diameter642.9 mm · 25.31 in
Sidewall height118.3 mm
Circumference2,019.7 mm
Revolutions / mile796.8
Speedometer & odometer error

The new tire changes overall diameter by +3.44%. With a speedometer calibrated to the original tire, that same percentage is how far the speedometer and odometer read off — a taller tire means your true speed is higher than indicated and the odometer under-counts distance.

Speedo showsTrue speedSpeedo showsTrue speed
40 km/h41.4 km/h25 mph26 mph
60 km/h62.1 km/h37 mph39 mph
80 km/h82.8 km/h50 mph51 mph
100 km/h103.4 km/h62 mph64 mph
120 km/h124.1 km/h75 mph77 mph

See individual specs: 185/65R15 · 215/55R16. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.