Tire Size Box

235/65R17 vs 235/75R17

235/75R17 compared with 235/65R17

+6.4% diameter, 0.0" width

235/75R17 is 30.88" tall vs 29.03". More than the 3% rule of thumb, so check carefully before switching.

29.0"17" rim6.0"9.3" wide
235/65R17 (solid) compared with 235/75R17 (dashed outline), drawn to scale

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

63.8 mph

235/75R17 is +1.85 inches (+6.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R17235/75R17Difference%
Overall diameter29.03"30.88"+1.85"+6.4%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.01"6.94"+0.93"+15.4%
Circumference91.19"97.01"+5.81"+6.4%
Revolutions per mile694.8653.2−41.6−6.0%

Speedometer difference

If your vehicle came with 235/65R17 and you fit 235/75R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.3 mph+1.3 mph
30 mph31.9 mph+1.9 mph
40 mph42.5 mph+2.5 mph
50 mph53.2 mph+3.2 mph
60 mph63.8 mph+3.8 mph
65 mph69.1 mph+4.1 mph
70 mph74.5 mph+4.5 mph
75 mph79.8 mph+4.8 mph
80 mph85.1 mph+5.1 mph

Each size on its own

Questions

Which is bigger, 235/65R17 or 235/75R17?
235/75R17 is taller by 1.85 inches (30.88" vs 29.03"). 235/65R17 is the same width.
Can I replace 235/65R17 with 235/75R17?
It is not recommended without checking carefully. The diameter difference is +6.4%, 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 235/75R17 change my speedometer?
When your speedometer reads 60 mph with 235/75R17 fitted (calibrated for 235/65R17), your real speed is 63.8 mph. Your odometer will under-count miles by about 6.4%.
Will 235/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

Other comparisons