Tire Size Box

275/60R18 vs 275/65R18

275/65R18 compared with 275/60R18

+3.5% diameter, 0.0" width

275/65R18 is 32.07" tall vs 30.99". More than the 3% rule of thumb, so check carefully before switching.

31.0"18" rim6.5"10.8" wide
275/60R18 (solid) compared with 275/65R18 (dashed outline), drawn to scale

With 275/65R18 tires, when your speedometer says 60 mph you are really going

62.1 mph

275/65R18 is +1.08 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/60R18275/65R18Difference%
Overall diameter30.99"32.07"+1.08"+3.5%
Section width10.83"10.83"0.00"0.0%
Sidewall height6.50"7.04"+0.54"+8.3%
Circumference97.36"100.77"+3.40"+3.5%
Revolutions per mile650.7628.8−22.0−3.4%

Speedometer difference

If your vehicle came with 275/60R18 and you fit 275/65R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 275/60R18 or 275/65R18?
275/65R18 is taller by 1.08 inches (32.07" vs 30.99"). 275/60R18 is the same width.
Can I replace 275/60R18 with 275/65R18?
It is not recommended without checking carefully. The diameter difference is +3.5%, 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 275/65R18 change my speedometer?
When your speedometer reads 60 mph with 275/65R18 fitted (calibrated for 275/60R18), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 275/65R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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