Tire Size Box

275/25R20 vs 265/30R20

265/30R20 compared with 275/25R20

+3.3% diameter, −0.4" width

265/30R20 is 26.26" tall vs 25.41". More than the 3% rule of thumb, so check carefully before switching.

25.4"20" rim2.7"10.8" wide
275/25R20 (solid) compared with 265/30R20 (dashed outline), drawn to scale

With 265/30R20 tires, when your speedometer says 60 mph you are really going

62.0 mph

265/30R20 is +0.85 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/25R20265/30R20Difference%
Overall diameter25.41"26.26"+0.85"+3.3%
Section width10.83"10.43"−0.39"−3.6%
Sidewall height2.71"3.13"+0.42"+15.6%
Circumference79.84"82.50"+2.66"+3.3%
Revolutions per mile793.6768.0−25.6−3.2%

Speedometer difference

If your vehicle came with 275/25R20 and you fit 265/30R20, 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, 275/25R20 or 265/30R20?
265/30R20 is taller by 0.85 inches (26.26" vs 25.41"). 275/25R20 is wider by 0.39 inches.
Can I replace 275/25R20 with 265/30R20?
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 265/30R20 change my speedometer?
When your speedometer reads 60 mph with 265/30R20 fitted (calibrated for 275/25R20), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 265/30R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.42 inches of ground clearance at the axle.

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