Tire Size Box

275/30R20 vs 275/35R20

275/35R20 compared with 275/30R20

+4.1% diameter, 0.0" width

275/35R20 is 27.58" tall vs 26.50". More than the 3% rule of thumb, so check carefully before switching.

26.5"20" rim3.2"10.8" wide
275/30R20 (solid) compared with 275/35R20 (dashed outline), drawn to scale

With 275/35R20 tires, when your speedometer says 60 mph you are really going

62.5 mph

275/35R20 is +1.08 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/30R20275/35R20Difference%
Overall diameter26.50"27.58"+1.08"+4.1%
Section width10.83"10.83"0.00"0.0%
Sidewall height3.25"3.79"+0.54"+16.7%
Circumference83.24"86.64"+3.40"+4.1%
Revolutions per mile761.2731.3−29.9−3.9%

Speedometer difference

If your vehicle came with 275/30R20 and you fit 275/35R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 275/30R20 or 275/35R20?
275/35R20 is taller by 1.08 inches (27.58" vs 26.50"). 275/30R20 is the same width.
Can I replace 275/30R20 with 275/35R20?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 275/35R20 change my speedometer?
When your speedometer reads 60 mph with 275/35R20 fitted (calibrated for 275/30R20), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 275/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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