Tire Size Box

265/65R18 vs 265/70R18

265/70R18 compared with 265/65R18

+3.3% diameter, 0.0" width

265/70R18 is 32.61" tall vs 31.56". More than the 3% rule of thumb, so check carefully before switching.

31.6"18" rim6.8"10.4" wide
265/65R18 (solid) compared with 265/70R18 (dashed outline), drawn to scale

With 265/70R18 tires, when your speedometer says 60 mph you are really going

62.0 mph

265/70R18 is +1.04 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/65R18265/70R18Difference%
Overall diameter31.56"32.61"+1.04"+3.3%
Section width10.43"10.43"0.00"0.0%
Sidewall height6.78"7.30"+0.52"+7.7%
Circumference99.16"102.44"+3.28"+3.3%
Revolutions per mile639.0618.5−20.4−3.2%

Speedometer difference

If your vehicle came with 265/65R18 and you fit 265/70R18, 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 mph41.3 mph+1.3 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 265/65R18 or 265/70R18?
265/70R18 is taller by 1.04 inches (32.61" vs 31.56"). 265/65R18 is the same width.
Can I replace 265/65R18 with 265/70R18?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 265/70R18 change my speedometer?
When your speedometer reads 60 mph with 265/70R18 fitted (calibrated for 265/65R18), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 265/70R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.52 inches of ground clearance at the axle.

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