What is the diameter difference between 255/35R19 and 265/30R19?

255/35R19 has an overall diameter of 26.03 inches (661 mm). 265/30R19 is 25.26 inches (642 mm). That's a 0.77 inch (20 mm) difference — 265/30R19 is shorter.

Will 265/30R19 cause speedometer error on a car fitted with 255/35R19?

Swapping 255/35R19 for 265/30R19 produces a speedometer error of about 2.9%. Your speedometer will read higher than your actual speed — a 60 mph indicated reading is really 58.2 mph. Anything under 3% is usually acceptable without recalibration.

How many revolutions per mile does each size do?

255/35R19 turns 775 revs per mile. 265/30R19 turns 798 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.

What's the sidewall height difference?

255/35R19 has a sidewall of 89 mm (3.51 in). 265/30R19 sidewall is 80 mm (3.13 in). Lower-profile sidewalls give sharper steering response but less bump compliance.

Is 265/30R19 a safe plus-size upgrade from 255/35R19?

A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 2.9%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.

Tire size comparison

255/35R19 vs 265/30R19

Overall diameter, sidewall, revs per mile, and speedometer error — 255/35R19 is the taller tire, with a 2.9% speedo delta when swapping.

255/35R19

26.03in

661 mm overall diameter

265/30R19

25.26in

642 mm overall diameter

Diameter Δ

0.77 in

Speedo error

2.9%

255/35R19 revs/mi

775

265/30R19 revs/mi

798

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	255/35R19	265/30R19
Section width	255 mm	265 mm
Aspect ratio	35	30
Wheel diameter	19″	19″
Sidewall height	89 mm	80 mm
Overall diameter	26.03 in (661 mm)	25.26 in (642 mm)
Circumference	81.77 in	79.36 in
Revolutions / mile	775	798

Other comparisons for these sizes

235/45R17 vs 255/35R19 245/40R18 vs 255/35R19 255/35R18 vs 265/30R19 255/40R18 vs 255/35R19 265/35R18 vs 265/30R19 235/35R19 vs 255/35R19 245/35R19 vs 255/35R19 245/40R19 vs 255/35R19 255/35R19 vs 265/30R20 255/35R19 vs 255/30R20

FAQ

Frequently asked

What is the diameter difference between 255/35R19 and 265/30R19?: 255/35R19 has an overall diameter of 26.03 inches (661 mm). 265/30R19 is 25.26 inches (642 mm). That's a 0.77 inch (20 mm) difference — 265/30R19 is shorter.
Will 265/30R19 cause speedometer error on a car fitted with 255/35R19?: Swapping 255/35R19 for 265/30R19 produces a speedometer error of about 2.9%. Your speedometer will read higher than your actual speed — a 60 mph indicated reading is really 58.2 mph. Anything under 3% is usually acceptable without recalibration.
How many revolutions per mile does each size do?: 255/35R19 turns 775 revs per mile. 265/30R19 turns 798 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.
What's the sidewall height difference?: 255/35R19 has a sidewall of 89 mm (3.51 in). 265/30R19 sidewall is 80 mm (3.13 in). Lower-profile sidewalls give sharper steering response but less bump compliance.
Is 265/30R19 a safe plus-size upgrade from 255/35R19?: A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 2.9%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.