What is the diameter difference between 215/60R16 and 235/50R18?

215/60R16 has an overall diameter of 26.16 inches (664 mm). 235/50R18 is 27.25 inches (692 mm). That's a 1.09 inch (28 mm) difference — 235/50R18 is taller.

Will 235/50R18 cause speedometer error on a car fitted with 215/60R16?

Swapping 215/60R16 for 235/50R18 produces a speedometer error of about 4.2%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 62.5 mph. Anything under 3% is usually acceptable without recalibration.

How many revolutions per mile does each size do?

215/60R16 turns 771 revs per mile. 235/50R18 turns 740 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.

What's the sidewall height difference?

215/60R16 has a sidewall of 129 mm (5.08 in). 235/50R18 sidewall is 118 mm (4.63 in). Lower-profile sidewalls give sharper steering response but less bump compliance.

Is 235/50R18 a safe plus-size upgrade from 215/60R16?

A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 4.2%. This swap is outside the typical ±3% safe range and may require speedometer recalibration or affect ABS / traction control behaviour.

Tire size comparison

215/60R16 vs 235/50R18

Overall diameter, sidewall, revs per mile, and speedometer error — 235/50R18 is the taller tire, with a 4.2% speedo delta when swapping.

215/60R16

26.16in

664 mm overall diameter

235/50R18

27.25in

692 mm overall diameter

Diameter Δ

1.09 in

Speedo error

4.2%

215/60R16 revs/mi

771

235/50R18 revs/mi

740

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	215/60R16	235/50R18
Section width	215 mm	235 mm
Aspect ratio	60	50
Wheel diameter	16″	18″
Sidewall height	129 mm	118 mm
Overall diameter	26.16 in (664 mm)	27.25 in (692 mm)
Circumference	82.18 in	85.61 in
Revolutions / mile	771	740

Other comparisons for these sizes

205/65R15 vs 215/60R16 205/60R16 vs 215/60R16 215/60R16 vs 215/55R17 215/60R16 vs 225/60R16 235/55R17 vs 235/50R18 235/45R18 vs 235/50R18 235/50R18 vs 245/45R19 235/50R18 vs 245/45R18

FAQ

Frequently asked

What is the diameter difference between 215/60R16 and 235/50R18?: 215/60R16 has an overall diameter of 26.16 inches (664 mm). 235/50R18 is 27.25 inches (692 mm). That's a 1.09 inch (28 mm) difference — 235/50R18 is taller.
Will 235/50R18 cause speedometer error on a car fitted with 215/60R16?: Swapping 215/60R16 for 235/50R18 produces a speedometer error of about 4.2%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 62.5 mph. Anything under 3% is usually acceptable without recalibration.
How many revolutions per mile does each size do?: 215/60R16 turns 771 revs per mile. 235/50R18 turns 740 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.
What's the sidewall height difference?: 215/60R16 has a sidewall of 129 mm (5.08 in). 235/50R18 sidewall is 118 mm (4.63 in). Lower-profile sidewalls give sharper steering response but less bump compliance.
Is 235/50R18 a safe plus-size upgrade from 215/60R16?: A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 4.2%. This swap is outside the typical ±3% safe range and may require speedometer recalibration or affect ABS / traction control behaviour.