Tire Size Box

245/65R20 vs 265/65R20

265/65R20 compared with 245/65R20

+3.1% diameter, +0.8" width

265/65R20 is 33.56" tall vs 32.54". More than the 3% rule of thumb, so check carefully before switching.

32.5"20" rim6.3"9.6" wide
245/65R20 (solid) compared with 265/65R20 (dashed outline), drawn to scale

With 265/65R20 tires, when your speedometer says 60 mph you are really going

61.9 mph

265/65R20 is +1.02 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/65R20265/65R20Difference%
Overall diameter32.54"33.56"+1.02"+3.1%
Section width9.65"10.43"+0.79"+8.2%
Sidewall height6.27"6.78"+0.51"+8.2%
Circumference102.23"105.44"+3.22"+3.1%
Revolutions per mile619.8600.9−18.9−3.0%

Speedometer difference

If your vehicle came with 245/65R20 and you fit 265/65R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 245/65R20 or 265/65R20?
265/65R20 is taller by 1.02 inches (33.56" vs 32.54"). 265/65R20 is wider by 0.79 inches.
Can I replace 245/65R20 with 265/65R20?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 265/65R20 change my speedometer?
When your speedometer reads 60 mph with 265/65R20 fitted (calibrated for 245/65R20), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 265/65R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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