Tire Size Box

235/70R15 vs 235/75R15

235/75R15 compared with 235/70R15

+3.3% diameter, 0.0" width

235/75R15 is 28.88" tall vs 27.95". More than the 3% rule of thumb, so check carefully before switching.

28.0"15" rim6.5"9.3" wide
235/70R15 (solid) compared with 235/75R15 (dashed outline), drawn to scale

With 235/75R15 tires, when your speedometer says 60 mph you are really going

62.0 mph

235/75R15 is +0.93 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/70R15235/75R15Difference%
Overall diameter27.95"28.88"+0.93"+3.3%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.48"6.94"+0.46"+7.1%
Circumference87.82"90.72"+2.91"+3.3%
Revolutions per mile721.5698.4−23.1−3.2%

Speedometer difference

If your vehicle came with 235/70R15 and you fit 235/75R15, 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 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 235/70R15 or 235/75R15?
235/75R15 is taller by 0.93 inches (28.88" vs 27.95"). 235/70R15 is the same width.
Can I replace 235/70R15 with 235/75R15?
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 235/75R15 change my speedometer?
When your speedometer reads 60 mph with 235/75R15 fitted (calibrated for 235/70R15), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 235/75R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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