Tire Size Box

235/65R15 vs 235/70R15

235/70R15 compared with 235/65R15

+3.4% diameter, 0.0" width

235/70R15 is 27.95" 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 235/70R15 (dashed outline), drawn to scale

With 235/70R15 tires, when your speedometer says 60 mph you are really going

62.1 mph

235/70R15 is +0.93 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/65R15235/70R15Difference%
Overall diameter27.03"27.95"+0.93"+3.4%
Section width9.25"9.25"0.00"0.0%
Sidewall height6.01"6.48"+0.46"+7.7%
Circumference84.91"87.82"+2.91"+3.4%
Revolutions per mile746.2721.5−24.7−3.3%

Speedometer difference

If your vehicle came with 235/65R15 and you fit 235/70R15, 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 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 235/65R15 or 235/70R15?
235/70R15 is taller by 0.93 inches (27.95" vs 27.03"). 235/65R15 is the same width.
Can I replace 235/65R15 with 235/70R15?
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 235/70R15 change my speedometer?
When your speedometer reads 60 mph with 235/70R15 fitted (calibrated for 235/65R15), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 235/70R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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