265/50R21 vs 275/50R21

275/50R21 is 0.39 in (10.0 mm) taller than 265/50R21, a +1.25% diameter difference. With the speedometer set for 265/50R21, an indicated 60 mph is 60.8 mph on 275/50R21.

Is this a safe swap?

Diameter difference +1.25%: within the ±3% guideline

By overall diameter alone, 275/50R21 falls inside the ±3% range commonly used as a guideline when replacing 265/50R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

265/50R21 vs 275/50R21 differences
Measurement	265/50R21	275/50R21	Difference	% diff
Overall diameter	31.43 in (798.4 mm)	31.83 in (808.4 mm)	+0.39 in (+10.0 mm)	+1.25%
Sidewall height	5.22 in (132.5 mm)	5.41 in (137.5 mm)	+0.20 in (+5.0 mm)	+3.77%
Section width	10.43 in (265.0 mm)	10.83 in (275.0 mm)	+0.39 in (+10.0 mm)	+3.77%
Circumference	98.75 in (2,508.2 mm)	99.99 in (2,539.7 mm)	+1.24 in (+31.4 mm)	+1.25%
Revolutions per mile	642	634	−8	−1.24%

True speed with the speedometer calibrated for 265/50R21
Indicated	Actual on 265/50R21	Actual on 275/50R21	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 275/50R21 raises the vehicle by 0.20 in (5.0 mm) at the axle (half the +10.0 mm diameter difference).

275/50R21 is 0.39 in taller than 265/50R21 and 10 mm wider, a 1.25% difference in overall diameter.

With the speedometer calibrated for 265/50R21, an indicated 60 mph is actually 60.8 mph on 275/50R21, and revolutions per mile change from 642 to 634.

Both sizes mount on 21-inch wheels.

Size pages

Other comparisons with 265/50R21

Other comparisons with 275/50R21

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.