Tire Size Box

245/70R18 vs 265/70R18

265/70R18 compared with 245/70R18

+3.5% diameter, +0.8" width

265/70R18 is 32.61" tall vs 31.50". More than the 3% rule of thumb, so check carefully before switching.

31.5"18" rim6.8"9.6" wide
245/70R18 (solid) compared with 265/70R18 (dashed outline), drawn to scale

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

62.1 mph

265/70R18 is +1.10 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/70R18265/70R18Difference%
Overall diameter31.50"32.61"+1.10"+3.5%
Section width9.65"10.43"+0.79"+8.2%
Sidewall height6.75"7.30"+0.55"+8.2%
Circumference98.97"102.44"+3.46"+3.5%
Revolutions per mile640.2618.5−21.6−3.4%

Speedometer difference

If your vehicle came with 245/70R18 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 mph41.4 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, 245/70R18 or 265/70R18?
265/70R18 is taller by 1.10 inches (32.61" vs 31.50"). 265/70R18 is wider by 0.79 inches.
Can I replace 245/70R18 with 265/70R18?
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 265/70R18 change my speedometer?
When your speedometer reads 60 mph with 265/70R18 fitted (calibrated for 245/70R18), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 265/70R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.55 inches of ground clearance at the axle.

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