TireSizesFinder

275/40R17 vs 275/30R19

275/30R19 is 0.17 in (4.2 mm) shorter than 275/40R17, a −0.64% diameter difference. With the speedometer set for 275/40R17, an indicated 60 mph is 59.6 mph on 275/30R19.

Is this a safe swap?

Diameter difference −0.64%: under 1%

By overall diameter alone, 275/30R19 is a near match for 275/40R17; 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: 275/40R17 (25.66 in) vs 275/30R19 (25.50 in)275/40R1725.66 in × 10.83 in275/30R1925.50 in × 10.83 in
Side profile and tread width, drawn to the same scale.
275/40R17 vs 275/30R19 differences
Measurement275/40R17275/30R19Difference% diff
Overall diameter25.66 in (651.8 mm)25.50 in (647.6 mm)−0.17 in (−4.2 mm)−0.64%
Sidewall height4.33 in (110.0 mm)3.25 in (82.5 mm)−1.08 in (−27.5 mm)−25.00%
Section width10.83 in (275.0 mm)10.83 in (275.0 mm)0.00 in (0.0 mm)0.00%
Circumference80.62 in (2,047.7 mm)80.10 in (2,034.5 mm)−0.52 in (−13.2 mm)−0.64%
Revolutions per mile786791+5+0.65%
True speed with the speedometer calibrated for 275/40R17
IndicatedActual on 275/40R17Actual on 275/30R19Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.5 mph−0.5 mph

Ride-height change: 275/30R19 lowers the vehicle by 0.08 in (2.1 mm) at the axle (half the −4.2 mm diameter difference).

275/30R19 is 0.17 in shorter than 275/40R17 and the same width, a 0.64% difference in overall diameter.

With the speedometer calibrated for 275/40R17, an indicated 60 mph is actually 59.6 mph on 275/30R19, and revolutions per mile change from 786 to 791.

275/30R19 mounts on a 19-inch wheel, a plus-2 fitment from the 17-inch wheel of 275/40R17.

Size pages

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