Tire Size Box

245/65R18 vs 265/65R18

265/65R18 compared with 245/65R18

+3.4% diameter, +0.8" width

265/65R18 is 31.56" tall vs 30.54". More than the 3% rule of thumb, so check carefully before switching.

30.5"18" rim6.3"9.6" wide
245/65R18 (solid) compared with 265/65R18 (dashed outline), drawn to scale

With 265/65R18 tires, when your speedometer says 60 mph you are really going

62.0 mph

265/65R18 is +1.02 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/65R18265/65R18Difference%
Overall diameter30.54"31.56"+1.02"+3.4%
Section width9.65"10.43"+0.79"+8.2%
Sidewall height6.27"6.78"+0.51"+8.2%
Circumference95.94"99.16"+3.22"+3.4%
Revolutions per mile660.4639.0−21.4−3.2%

Speedometer difference

If your vehicle came with 245/65R18 and you fit 265/65R18, 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 mph41.3 mph+1.3 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 245/65R18 or 265/65R18?
265/65R18 is taller by 1.02 inches (31.56" vs 30.54"). 265/65R18 is wider by 0.79 inches.
Can I replace 245/65R18 with 265/65R18?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 265/65R18 change my speedometer?
When your speedometer reads 60 mph with 265/65R18 fitted (calibrated for 245/65R18), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 265/65R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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