Tire Size Box

275/30R22 vs 275/40R22

275/40R22 compared with 275/30R22

+7.6% diameter, 0.0" width

275/40R22 is 30.66" tall vs 28.50". More than the 3% rule of thumb, so check carefully before switching.

28.5"22" rim3.2"10.8" wide
275/30R22 (solid) compared with 275/40R22 (dashed outline), drawn to scale

With 275/40R22 tires, when your speedometer says 60 mph you are really going

64.6 mph

275/40R22 is +2.17 inches (+7.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/30R22275/40R22Difference%
Overall diameter28.50"30.66"+2.17"+7.6%
Section width10.83"10.83"0.00"0.0%
Sidewall height3.25"4.33"+1.08"+33.3%
Circumference89.52"96.33"+6.80"+7.6%
Revolutions per mile707.8657.8−50.0−7.1%

Speedometer difference

If your vehicle came with 275/30R22 and you fit 275/40R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.3 mph+2.3 mph
40 mph43.0 mph+3.0 mph
50 mph53.8 mph+3.8 mph
60 mph64.6 mph+4.6 mph
65 mph69.9 mph+4.9 mph
70 mph75.3 mph+5.3 mph
75 mph80.7 mph+5.7 mph
80 mph86.1 mph+6.1 mph

Each size on its own

Questions

Which is bigger, 275/30R22 or 275/40R22?
275/40R22 is taller by 2.17 inches (30.66" vs 28.50"). 275/30R22 is the same width.
Can I replace 275/30R22 with 275/40R22?
It is not recommended without checking carefully. The diameter difference is +7.6%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 275/40R22 change my speedometer?
When your speedometer reads 60 mph with 275/40R22 fitted (calibrated for 275/30R22), your real speed is 64.6 mph. Your odometer will under-count miles by about 7.6%.
Will 275/40R22 lift my vehicle?
Ride height changes by half the diameter difference: +1.08 inches of ground clearance at the axle.

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