Tire Size Box

225/80R15 vs 225/85R15

225/85R15 compared with 225/80R15

+3.0% diameter, 0.0" width

225/85R15 is 30.06" tall vs 29.17". More than the 3% rule of thumb, so check carefully before switching.

29.2"15" rim7.1"8.9" wide
225/80R15 (solid) compared with 225/85R15 (dashed outline), drawn to scale

With 225/85R15 tires, when your speedometer says 60 mph you are really going

61.8 mph

225/85R15 is +0.89 inches (+3.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/80R15225/85R15Difference%
Overall diameter29.17"30.06"+0.89"+3.0%
Section width8.86"8.86"0.00"0.0%
Sidewall height7.09"7.53"+0.44"+6.3%
Circumference91.65"94.43"+2.78"+3.0%
Revolutions per mile691.3670.9−20.4−2.9%

Speedometer difference

If your vehicle came with 225/80R15 and you fit 225/85R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.1 mph+2.1 mph
75 mph77.3 mph+2.3 mph
80 mph82.4 mph+2.4 mph

Each size on its own

Questions

Which is bigger, 225/80R15 or 225/85R15?
225/85R15 is taller by 0.89 inches (30.06" vs 29.17"). 225/80R15 is the same width.
Can I replace 225/80R15 with 225/85R15?
It is not recommended without checking carefully. The diameter difference is +3.0%, 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 225/85R15 change my speedometer?
When your speedometer reads 60 mph with 225/85R15 fitted (calibrated for 225/80R15), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.0%.
Will 225/85R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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