Tire Size Box

225/30R21 vs 225/35R21

225/35R21 compared with 225/30R21

+3.4% diameter, 0.0" width

225/35R21 is 27.20" tall vs 26.31". More than the 3% rule of thumb, so check carefully before switching.

26.3"21" rim2.7"8.9" wide
225/30R21 (solid) compared with 225/35R21 (dashed outline), drawn to scale

With 225/35R21 tires, when your speedometer says 60 mph you are really going

62.0 mph

225/35R21 is +0.89 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/30R21225/35R21Difference%
Overall diameter26.31"27.20"+0.89"+3.4%
Section width8.86"8.86"0.00"0.0%
Sidewall height2.66"3.10"+0.44"+16.7%
Circumference82.67"85.45"+2.78"+3.4%
Revolutions per mile766.4741.5−25.0−3.3%

Speedometer difference

If your vehicle came with 225/30R21 and you fit 225/35R21, 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 mph72.4 mph+2.4 mph
75 mph77.5 mph+2.5 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 225/30R21 or 225/35R21?
225/35R21 is taller by 0.89 inches (27.20" vs 26.31"). 225/30R21 is the same width.
Can I replace 225/30R21 with 225/35R21?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 225/35R21 change my speedometer?
When your speedometer reads 60 mph with 225/35R21 fitted (calibrated for 225/30R21), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 225/35R21 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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