Tire Size Box

225/70R15 vs 225/80R15

225/80R15 compared with 225/70R15

+6.5% diameter, 0.0" width

225/80R15 is 29.17" tall vs 27.40". More than the 3% rule of thumb, so check carefully before switching.

27.4"15" rim6.2"8.9" wide
225/70R15 (solid) compared with 225/80R15 (dashed outline), drawn to scale

With 225/80R15 tires, when your speedometer says 60 mph you are really going

63.9 mph

225/80R15 is +1.77 inches (+6.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/70R15225/80R15Difference%
Overall diameter27.40"29.17"+1.77"+6.5%
Section width8.86"8.86"0.00"0.0%
Sidewall height6.20"7.09"+0.89"+14.3%
Circumference86.08"91.65"+5.57"+6.5%
Revolutions per mile736.0691.3−44.7−6.1%

Speedometer difference

If your vehicle came with 225/70R15 and you fit 225/80R15, 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 mph42.6 mph+2.6 mph
50 mph53.2 mph+3.2 mph
60 mph63.9 mph+3.9 mph
65 mph69.2 mph+4.2 mph
70 mph74.5 mph+4.5 mph
75 mph79.8 mph+4.8 mph
80 mph85.2 mph+5.2 mph

Each size on its own

Questions

Which is bigger, 225/70R15 or 225/80R15?
225/80R15 is taller by 1.77 inches (29.17" vs 27.40"). 225/70R15 is the same width.
Can I replace 225/70R15 with 225/80R15?
It is not recommended without checking carefully. The diameter difference is +6.5%, 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 225/80R15 change my speedometer?
When your speedometer reads 60 mph with 225/80R15 fitted (calibrated for 225/70R15), your real speed is 63.9 mph. Your odometer will under-count miles by about 6.5%.
Will 225/80R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.89 inches of ground clearance at the axle.

Other comparisons