Tire Size Box

295/45R20 vs 295/55R20

295/55R20 compared with 295/45R20

+7.6% diameter, 0.0" width

295/55R20 is 32.78" tall vs 30.45". More than the 3% rule of thumb, so check carefully before switching.

30.5"20" rim5.2"11.6" wide
295/45R20 (solid) compared with 295/55R20 (dashed outline), drawn to scale

With 295/55R20 tires, when your speedometer says 60 mph you are really going

64.6 mph

295/55R20 is +2.32 inches (+7.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/45R20295/55R20Difference%
Overall diameter30.45"32.78"+2.32"+7.6%
Section width11.61"11.61"0.00"0.0%
Sidewall height5.23"6.39"+1.16"+22.2%
Circumference95.67"102.97"+7.30"+7.6%
Revolutions per mile662.3615.3−46.9−7.1%

Speedometer difference

If your vehicle came with 295/45R20 and you fit 295/55R20, 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 mph43.1 mph+3.1 mph
50 mph53.8 mph+3.8 mph
60 mph64.6 mph+4.6 mph
65 mph70.0 mph+5.0 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, 295/45R20 or 295/55R20?
295/55R20 is taller by 2.32 inches (32.78" vs 30.45"). 295/45R20 is the same width.
Can I replace 295/45R20 with 295/55R20?
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 295/55R20 change my speedometer?
When your speedometer reads 60 mph with 295/55R20 fitted (calibrated for 295/45R20), your real speed is 64.6 mph. Your odometer will under-count miles by about 7.6%.
Will 295/55R20 lift my vehicle?
Ride height changes by half the diameter difference: +1.16 inches of ground clearance at the axle.

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