TireSizesFinder

265/40R21 vs 275/40R21

275/40R21 is 0.31 in (8.0 mm) taller than 265/40R21, a +1.07% diameter difference. With the speedometer set for 265/40R21, an indicated 60 mph is 60.6 mph on 275/40R21.

Is this a safe swap?

Diameter difference +1.07%: within the ±3% guideline

By overall diameter alone, 275/40R21 falls inside the ±3% range commonly used as a guideline when replacing 265/40R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/40R21 (29.35 in) vs 275/40R21 (29.66 in)265/40R2129.35 in × 10.43 in275/40R2129.66 in × 10.83 in
Side profile and tread width, drawn to the same scale.
265/40R21 vs 275/40R21 differences
Measurement265/40R21275/40R21Difference% diff
Overall diameter29.35 in (745.4 mm)29.66 in (753.4 mm)+0.31 in (+8.0 mm)+1.07%
Sidewall height4.17 in (106.0 mm)4.33 in (110.0 mm)+0.16 in (+4.0 mm)+3.77%
Section width10.43 in (265.0 mm)10.83 in (275.0 mm)+0.39 in (+10.0 mm)+3.77%
Circumference92.19 in (2,341.7 mm)93.18 in (2,366.9 mm)+0.99 in (+25.1 mm)+1.07%
Revolutions per mile687680−7−1.06%
True speed with the speedometer calibrated for 265/40R21
IndicatedActual on 265/40R21Actual on 275/40R21Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.6 mph+0.6 mph
75 mph75.0 mph75.8 mph+0.8 mph

Ride-height change: 275/40R21 raises the vehicle by 0.16 in (4.0 mm) at the axle (half the +8.0 mm diameter difference).

275/40R21 is 0.31 in taller than 265/40R21 and 10 mm wider, a 1.07% difference in overall diameter.

With the speedometer calibrated for 265/40R21, an indicated 60 mph is actually 60.6 mph on 275/40R21, and revolutions per mile change from 687 to 680.

Both sizes mount on 21-inch wheels.

Size pages

Other comparisons with 265/40R21

Other comparisons with 275/40R21

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.