Tire Size Box

275/75R15 vs 275/85R15

275/85R15 compared with 275/75R15

+6.9% diameter, 0.0" width

275/85R15 is 33.41" tall vs 31.24". More than the 3% rule of thumb, so check carefully before switching.

31.2"15" rim8.1"10.8" wide
275/75R15 (solid) compared with 275/85R15 (dashed outline), drawn to scale

With 275/85R15 tires, when your speedometer says 60 mph you are really going

64.2 mph

275/85R15 is +2.17 inches (+6.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/75R15275/85R15Difference%
Overall diameter31.24"33.41"+2.17"+6.9%
Section width10.83"10.83"0.00"0.0%
Sidewall height8.12"9.20"+1.08"+13.3%
Circumference98.14"104.95"+6.80"+6.9%
Revolutions per mile645.6603.7−41.8−6.5%

Speedometer difference

If your vehicle came with 275/75R15 and you fit 275/85R15, 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 mph42.8 mph+2.8 mph
50 mph53.5 mph+3.5 mph
60 mph64.2 mph+4.2 mph
65 mph69.5 mph+4.5 mph
70 mph74.9 mph+4.9 mph
75 mph80.2 mph+5.2 mph
80 mph85.5 mph+5.5 mph

Each size on its own

Questions

Which is bigger, 275/75R15 or 275/85R15?
275/85R15 is taller by 2.17 inches (33.41" vs 31.24"). 275/75R15 is the same width.
Can I replace 275/75R15 with 275/85R15?
It is not recommended without checking carefully. The diameter difference is +6.9%, 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 275/85R15 change my speedometer?
When your speedometer reads 60 mph with 275/85R15 fitted (calibrated for 275/75R15), your real speed is 64.2 mph. Your odometer will under-count miles by about 6.9%.
Will 275/85R15 lift my vehicle?
Ride height changes by half the diameter difference: +1.08 inches of ground clearance at the axle.

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