255/60R15 vs 255/70R15

255/70R15 is 2.0" taller than 255/60R15 (7.4%)

Diameter difference+7.42%diameter 27.05" → 29.06"
255/60R15255/70R15
255/60R15255/70R15Difference
Overall diameter27.05"29.06"+2.01"
Section width10.04"10.04"±0.00"
Sidewall height6.02"7.03"+1.00"
Circumference85.0"91.3"+6.3"
Revolutions per mile746694−52
Wheel diameter15"15"±0"

Speedometer

ShowsActualDiff
30 mph32.2 mph+2.2
45 mph48.3 mph+3.3
60 mph64.5 mph+4.5
70 mph75.2 mph+5.2
80 mph85.9 mph+5.9

Gear ratio to match

CurrentEquivalent
3.423.67
3.553.81
3.734.01
4.104.40

255/70R15 is 2.01" taller than 255/60R15, a +7.42% change in diameter. That is more than the 3% many tire shops use as a limit, so plan on recalibrating the speedometer and checking ABS and stability control.

Ground clearance changes by 1.00" (half the diameter change), and the tire needs 1.00" more room above it.

Both tires are the same width, 10.04".

Both fit a 15" wheel; the sidewall is 1.00" taller on 255/70R15.

Details: 255/60R15 in inches · 255/70R15 in inches · change sizes in the calculator

FAQ

What is the difference between 255/60R15 and 255/70R15?

255/70R15 is 2.01" taller (+7.42%) and 0.00" wider than 255/60R15.

Will 255/70R15 change my speedometer?

Yes, by +7.42%. When the speedometer shows 60 mph you would be going 64.5 mph.

Can I replace 255/60R15 with 255/70R15?

It is a +7.4% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.