TireSizesFinder

255/40R21 vs 295/35R21

295/35R21 is 0.10 in (2.5 mm) taller than 255/40R21, a +0.34% diameter difference. With the speedometer set for 255/40R21, an indicated 60 mph is 60.2 mph on 295/35R21.

Is this a safe swap?

Diameter difference +0.34%: under 1%

By overall diameter alone, 295/35R21 is a near match for 255/40R21; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 255/40R21 (29.03 in) vs 295/35R21 (29.13 in)255/40R2129.03 in × 10.04 in295/35R2129.13 in × 11.61 in
Side profile and tread width, drawn to the same scale.
255/40R21 vs 295/35R21 differences
Measurement255/40R21295/35R21Difference% diff
Overall diameter29.03 in (737.4 mm)29.13 in (739.9 mm)+0.10 in (+2.5 mm)+0.34%
Sidewall height4.02 in (102.0 mm)4.06 in (103.3 mm)+0.05 in (+1.3 mm)+1.23%
Section width10.04 in (255.0 mm)11.61 in (295.0 mm)+1.57 in (+40.0 mm)+15.69%
Circumference91.21 in (2,316.6 mm)91.51 in (2,324.5 mm)+0.31 in (+7.9 mm)+0.34%
Revolutions per mile695692−2−0.34%
True speed with the speedometer calibrated for 255/40R21
IndicatedActual on 255/40R21Actual on 295/35R21Difference
30 mph30.0 mph30.1 mph+0.1 mph
60 mph60.0 mph60.2 mph+0.2 mph
75 mph75.0 mph75.3 mph+0.3 mph

Ride-height change: 295/35R21 raises the vehicle by 0.05 in (1.3 mm) at the axle (half the +2.5 mm diameter difference).

295/35R21 is 0.10 in taller than 255/40R21 and 40 mm wider, a 0.34% difference in overall diameter.

With the speedometer calibrated for 255/40R21, an indicated 60 mph is actually 60.2 mph on 295/35R21, and revolutions per mile change from 695 to 692.

Both sizes mount on 21-inch wheels.

Size pages

Other comparisons with 255/40R21

Other comparisons with 295/35R21

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