What is the diameter difference between 245/45R19 and 265/35R21?

245/45R19 has an overall diameter of 27.68 inches (703 mm). 265/35R21 is 28.3 inches (719 mm). That's a 0.62 inch (16 mm) difference — 265/35R21 is taller.

Will 265/35R21 cause speedometer error on a car fitted with 245/45R19?

Swapping 245/45R19 for 265/35R21 produces a speedometer error of about 2.2%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 61.3 mph. Anything under 3% is usually acceptable without recalibration.

How many revolutions per mile does each size do?

245/45R19 turns 729 revs per mile. 265/35R21 turns 713 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.

What's the sidewall height difference?

245/45R19 has a sidewall of 110 mm (4.34 in). 265/35R21 sidewall is 93 mm (3.65 in). Lower-profile sidewalls give sharper steering response but less bump compliance.

Is 265/35R21 a safe plus-size upgrade from 245/45R19?

A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 2.2%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.

Tire size comparison

245/45R19 vs 265/35R21

Overall diameter, sidewall, revs per mile, and speedometer error — 265/35R21 is the taller tire, with a 2.2% speedo delta when swapping.

245/45R19

27.68in

703 mm overall diameter

265/35R21

28.3in

719 mm overall diameter

Diameter Δ

0.62 in

Speedo error

2.2%

245/45R19 revs/mi

729

265/35R21 revs/mi

713

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	245/45R19	265/35R21
Section width	245 mm	265 mm
Aspect ratio	45	35
Wheel diameter	19″	21″
Sidewall height	110 mm	93 mm
Overall diameter	27.68 in (703 mm)	28.3 in (719 mm)
Circumference	86.96 in	88.92 in
Revolutions / mile	729	713

Other comparisons for these sizes

235/50R18 vs 245/45R19 245/40R19 vs 245/45R19 245/45R19 vs 255/40R19 255/35R21 vs 265/35R21 265/35R21 vs 275/35R21 265/35R21 vs 275/30R21

FAQ

Frequently asked

What is the diameter difference between 245/45R19 and 265/35R21?: 245/45R19 has an overall diameter of 27.68 inches (703 mm). 265/35R21 is 28.3 inches (719 mm). That's a 0.62 inch (16 mm) difference — 265/35R21 is taller.
Will 265/35R21 cause speedometer error on a car fitted with 245/45R19?: Swapping 245/45R19 for 265/35R21 produces a speedometer error of about 2.2%. Your speedometer will read lower than your actual speed — a 60 mph indicated reading is really 61.3 mph. Anything under 3% is usually acceptable without recalibration.
How many revolutions per mile does each size do?: 245/45R19 turns 729 revs per mile. 265/35R21 turns 713 revs per mile. Taller tyres turn fewer times per mile, which lowers effective final-drive ratio.
What's the sidewall height difference?: 245/45R19 has a sidewall of 110 mm (4.34 in). 265/35R21 sidewall is 93 mm (3.65 in). Lower-profile sidewalls give sharper steering response but less bump compliance.
Is 265/35R21 a safe plus-size upgrade from 245/45R19?: A plus-size upgrade is considered safe when overall diameter stays within ±3% — here the difference is 2.2%. This swap is within the typical safe range; speedometer and ABS calibration should remain close to factory.