Tire Size Box

295/45R18 vs 295/55R18

295/55R18 compared with 295/45R18

+8.2% diameter, 0.0" width

295/55R18 is 30.78" tall vs 28.45". More than the 3% rule of thumb, so check carefully before switching.

28.5"18" rim5.2"11.6" wide
295/45R18 (solid) compared with 295/55R18 (dashed outline), drawn to scale

With 295/55R18 tires, when your speedometer says 60 mph you are really going

64.9 mph

295/55R18 is +2.32 inches (+8.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/45R18295/55R18Difference%
Overall diameter28.45"30.78"+2.32"+8.2%
Section width11.61"11.61"0.00"0.0%
Sidewall height5.23"6.39"+1.16"+22.2%
Circumference89.39"96.68"+7.30"+8.2%
Revolutions per mile708.8655.3−53.5−7.5%

Speedometer difference

If your vehicle came with 295/45R18 and you fit 295/55R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.4 mph+2.4 mph
40 mph43.3 mph+3.3 mph
50 mph54.1 mph+4.1 mph
60 mph64.9 mph+4.9 mph
65 mph70.3 mph+5.3 mph
70 mph75.7 mph+5.7 mph
75 mph81.1 mph+6.1 mph
80 mph86.5 mph+6.5 mph

Each size on its own

Questions

Which is bigger, 295/45R18 or 295/55R18?
295/55R18 is taller by 2.32 inches (30.78" vs 28.45"). 295/45R18 is the same width.
Can I replace 295/45R18 with 295/55R18?
It is not recommended without checking carefully. The diameter difference is +8.2%, 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 295/55R18 change my speedometer?
When your speedometer reads 60 mph with 295/55R18 fitted (calibrated for 295/45R18), your real speed is 64.9 mph. Your odometer will under-count miles by about 8.2%.
Will 295/55R18 lift my vehicle?
Ride height changes by half the diameter difference: +1.16 inches of ground clearance at the axle.

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