Tire Size Box

295/55R18 vs 295/65R18

295/65R18 compared with 295/55R18

+7.5% diameter, 0.0" width

295/65R18 is 33.10" tall vs 30.78". More than the 3% rule of thumb, so check carefully before switching.

30.8"18" rim6.4"11.6" wide
295/55R18 (solid) compared with 295/65R18 (dashed outline), drawn to scale

With 295/65R18 tires, when your speedometer says 60 mph you are really going

64.5 mph

295/65R18 is +2.32 inches (+7.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/55R18295/65R18Difference%
Overall diameter30.78"33.10"+2.32"+7.5%
Section width11.61"11.61"0.00"0.0%
Sidewall height6.39"7.55"+1.16"+18.2%
Circumference96.68"103.98"+7.30"+7.5%
Revolutions per mile655.3609.3−46.0−7.0%

Speedometer difference

If your vehicle came with 295/55R18 and you fit 295/65R18, 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 mph64.5 mph+4.5 mph
65 mph69.9 mph+4.9 mph
70 mph75.3 mph+5.3 mph
75 mph80.7 mph+5.7 mph
80 mph86.0 mph+6.0 mph

Each size on its own

Questions

Which is bigger, 295/55R18 or 295/65R18?
295/65R18 is taller by 2.32 inches (33.10" vs 30.78"). 295/55R18 is the same width.
Can I replace 295/55R18 with 295/65R18?
It is not recommended without checking carefully. The diameter difference is +7.5%, 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 295/65R18 change my speedometer?
When your speedometer reads 60 mph with 295/65R18 fitted (calibrated for 295/55R18), your real speed is 64.5 mph. Your odometer will under-count miles by about 7.5%.
Will 295/65R18 lift my vehicle?
Ride height changes by half the diameter difference: +1.16 inches of ground clearance at the axle.

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