Tire Size Box

245/75R18 vs 265/75R18

265/75R18 compared with 245/75R18

+3.6% diameter, +0.8" width

265/75R18 is 33.65" tall vs 32.47". More than the 3% rule of thumb, so check carefully before switching.

32.5"18" rim7.2"9.6" wide
245/75R18 (solid) compared with 265/75R18 (dashed outline), drawn to scale

With 265/75R18 tires, when your speedometer says 60 mph you are really going

62.2 mph

265/75R18 is +1.18 inches (+3.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/75R18265/75R18Difference%
Overall diameter32.47"33.65"+1.18"+3.6%
Section width9.65"10.43"+0.79"+8.2%
Sidewall height7.23"7.82"+0.59"+8.2%
Circumference102.00"105.71"+3.71"+3.6%
Revolutions per mile621.2599.4−21.8−3.5%

Speedometer difference

If your vehicle came with 245/75R18 and you fit 265/75R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.8 mph+1.8 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.5 mph+2.5 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 245/75R18 or 265/75R18?
265/75R18 is taller by 1.18 inches (33.65" vs 32.47"). 265/75R18 is wider by 0.79 inches.
Can I replace 245/75R18 with 265/75R18?
It is not recommended without checking carefully. The diameter difference is +3.6%, 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 265/75R18 change my speedometer?
When your speedometer reads 60 mph with 265/75R18 fitted (calibrated for 245/75R18), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.6%.
Will 265/75R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.59 inches of ground clearance at the axle.

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