Tire Size Box

235/65R15 vs 235/75R15

235/75R15 compared with 235/65R15

+6.8% diameter, 0.0" width

235/75R15 is 28.88" tall vs 27.03". More than the 3% rule of thumb, so check carefully before switching.

27.0"15" rim6.0"9.3" wide
235/65R15 (solid) compared with 235/75R15 (dashed outline), drawn to scale

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

64.1 mph

235/75R15 is +1.85 inches (+6.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R15235/75R15Difference%
Overall diameter27.03"28.88"+1.85"+6.8%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.01"6.94"+0.93"+15.4%
Circumference84.91"90.72"+5.81"+6.8%
Revolutions per mile746.2698.4−47.8−6.4%

Speedometer difference

If your vehicle came with 235/65R15 and you fit 235/75R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.7 mph+2.7 mph
50 mph53.4 mph+3.4 mph
60 mph64.1 mph+4.1 mph
65 mph69.5 mph+4.5 mph
70 mph74.8 mph+4.8 mph
75 mph80.1 mph+5.1 mph
80 mph85.5 mph+5.5 mph

Each size on its own

Questions

Which is bigger, 235/65R15 or 235/75R15?
235/75R15 is taller by 1.85 inches (28.88" vs 27.03"). 235/65R15 is the same width.
Can I replace 235/65R15 with 235/75R15?
It is not recommended without checking carefully. The diameter difference is +6.8%, 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 235/65R15), your real speed is 64.1 mph. Your odometer will under-count miles by about 6.8%.
Will 235/75R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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