Tire Size Box

235/70R17 vs 235/75R17

235/75R17 compared with 235/70R17

+3.1% diameter, 0.0" width

235/75R17 is 30.88" tall vs 29.95". More than the 3% rule of thumb, so check carefully before switching.

30.0"17" rim6.5"9.3" wide
235/70R17 (solid) compared with 235/75R17 (dashed outline), drawn to scale

With 235/75R17 tires, when your speedometer says 60 mph you are really going

61.9 mph

235/75R17 is +0.93 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/70R17235/75R17Difference%
Overall diameter29.95"30.88"+0.93"+3.1%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.48"6.94"+0.46"+7.1%
Circumference94.10"97.01"+2.91"+3.1%
Revolutions per mile673.3653.2−20.2−3.0%

Speedometer difference

If your vehicle came with 235/70R17 and you fit 235/75R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 235/70R17 or 235/75R17?
235/75R17 is taller by 0.93 inches (30.88" vs 29.95"). 235/70R17 is the same width.
Can I replace 235/70R17 with 235/75R17?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 235/75R17 change my speedometer?
When your speedometer reads 60 mph with 235/75R17 fitted (calibrated for 235/70R17), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 235/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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