Tire Size Box

275/25R21 vs 275/35R21

275/35R21 compared with 275/25R21

+8.2% diameter, 0.0" width

275/35R21 is 28.58" tall vs 26.41". More than the 3% rule of thumb, so check carefully before switching.

26.4"21" rim2.7"10.8" wide
275/25R21 (solid) compared with 275/35R21 (dashed outline), drawn to scale

With 275/35R21 tires, when your speedometer says 60 mph you are really going

64.9 mph

275/35R21 is +2.17 inches (+8.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/25R21275/35R21Difference%
Overall diameter26.41"28.58"+2.17"+8.2%
Section width10.83"10.83"0.00"0.0%
Sidewall height2.71"3.79"+1.08"+40.0%
Circumference82.98"89.78"+6.80"+8.2%
Revolutions per mile763.6705.7−57.9−7.6%

Speedometer difference

If your vehicle came with 275/25R21 and you fit 275/35R21, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.5 mph+2.5 mph
40 mph43.3 mph+3.3 mph
50 mph54.1 mph+4.1 mph
60 mph64.9 mph+4.9 mph
65 mph70.3 mph+5.3 mph
70 mph75.7 mph+5.7 mph
75 mph81.1 mph+6.1 mph
80 mph86.6 mph+6.6 mph

Each size on its own

Questions

Which is bigger, 275/25R21 or 275/35R21?
275/35R21 is taller by 2.17 inches (28.58" vs 26.41"). 275/25R21 is the same width.
Can I replace 275/25R21 with 275/35R21?
It is not recommended without checking carefully. The diameter difference is +8.2%, 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 275/35R21 change my speedometer?
When your speedometer reads 60 mph with 275/35R21 fitted (calibrated for 275/25R21), your real speed is 64.9 mph. Your odometer will under-count miles by about 8.2%.
Will 275/35R21 lift my vehicle?
Ride height changes by half the diameter difference: +1.08 inches of ground clearance at the axle.

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