What is the diameter difference between 285/30R22 and 305/30R22?

285/30R22 has an overall diameter of 28.73 inches (730 mm). 305/30R22 is 29.2 inches (742 mm). That's a 0.47 inch (12 mm) difference — 305/30R22 is taller.

Will 305/30R22 cause speedometer error on a car fitted with 285/30R22?

Swapping 285/30R22 for 305/30R22 produces a speedometer error of about 1.6%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 61 mph. Anything under 3% is usually acceptable without recalibration.

How many revolutions per mile does each size do?

285/30R22 turns 702 revs per mile. 305/30R22 turns 691 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.

What's the sidewall height difference?

285/30R22 has a sidewall of 86 mm (3.37 in). 305/30R22 sidewall is 92 mm (3.6 in). Lower-profile sidewalls give sharper steering response but less bump compliance.

Is 305/30R22 a safe plus-size upgrade from 285/30R22?

A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 1.6%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.

Tire size comparison

285/30R22 vs 305/30R22

Overall diameter, sidewall, revs per mile, and speedometer error — 305/30R22 is the taller tire, with a 1.6% speedo delta when swapping.

285/30R22

28.73in

730 mm overall diameter

305/30R22

29.2in

742 mm overall diameter

Diameter Δ

0.47 in

Speedo error

1.6%

285/30R22 revs/mi

702

305/30R22 revs/mi

691

Within the ±3% overall-diameter band usually considered safe for plus-sizing — speedometer and ABS calibration should stay close to factory.

Full spec

Side by side

Metric	285/30R22	305/30R22
Section width	285 mm	305 mm
Aspect ratio	30	30
Wheel diameter	22″	22″
Sidewall height	86 mm	92 mm
Overall diameter	28.73 in (730 mm)	29.2 in (742 mm)
Circumference	90.27 in	91.75 in
Revolutions / mile	702	691

Other comparisons for these sizes

275/35R21 vs 285/30R22 295/35R21 vs 305/30R22 285/30R22 vs 295/30R22 285/30R22 vs 285/35R22 295/30R22 vs 305/30R22 295/35R22 vs 305/30R22 305/30R22 vs 315/30R22 305/30R22 vs 325/30R22

FAQ

Frequently asked

What is the diameter difference between 285/30R22 and 305/30R22?: 285/30R22 has an overall diameter of 28.73 inches (730 mm). 305/30R22 is 29.2 inches (742 mm). That's a 0.47 inch (12 mm) difference — 305/30R22 is taller.
Will 305/30R22 cause speedometer error on a car fitted with 285/30R22?: Swapping 285/30R22 for 305/30R22 produces a speedometer error of about 1.6%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 61 mph. Anything under 3% is usually acceptable without recalibration.
How many revolutions per mile does each size do?: 285/30R22 turns 702 revs per mile. 305/30R22 turns 691 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.
What's the sidewall height difference?: 285/30R22 has a sidewall of 86 mm (3.37 in). 305/30R22 sidewall is 92 mm (3.6 in). Lower-profile sidewalls give sharper steering response but less bump compliance.
Is 305/30R22 a safe plus-size upgrade from 285/30R22?: A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 1.6%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.