Tire Size Box

275/65R15 vs 275/70R15

275/70R15 compared with 275/65R15

+3.7% diameter, 0.0" width

275/70R15 is 30.16" tall vs 29.07". More than the 3% rule of thumb, so check carefully before switching.

29.1"15" rim7.0"10.8" wide
275/65R15 (solid) compared with 275/70R15 (dashed outline), drawn to scale

With 275/70R15 tires, when your speedometer says 60 mph you are really going

62.2 mph

275/70R15 is +1.08 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/65R15275/70R15Difference%
Overall diameter29.07"30.16"+1.08"+3.7%
Section width10.83"10.83"0.00"0.0%
Sidewall height7.04"7.58"+0.54"+7.7%
Circumference91.34"94.74"+3.40"+3.7%
Revolutions per mile693.7668.8−24.9−3.6%

Speedometer difference

If your vehicle came with 275/65R15 and you fit 275/70R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 275/65R15 or 275/70R15?
275/70R15 is taller by 1.08 inches (30.16" vs 29.07"). 275/65R15 is the same width.
Can I replace 275/65R15 with 275/70R15?
It is not recommended without checking carefully. The diameter difference is +3.7%, 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 275/70R15 change my speedometer?
When your speedometer reads 60 mph with 275/70R15 fitted (calibrated for 275/65R15), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 275/70R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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