305/70R16 vs 315/75R16

315/75R16 is 1.8" taller than 305/70R16 (5.5%)

Diameter difference+5.46%diameter 32.81" → 34.60"
305/70R16315/75R16
305/70R16315/75R16Difference
Overall diameter32.81"34.60"+1.79"
Section width12.01"12.40"+0.39"
Sidewall height8.41"9.30"+0.90"
Circumference103.1"108.7"+5.6"
Revolutions per mile615583−32
Wheel diameter16"16"±0"

Speedometer

ShowsActualDiff
30 mph31.6 mph+1.6
45 mph47.5 mph+2.5
60 mph63.3 mph+3.3
70 mph73.8 mph+3.8
80 mph84.4 mph+4.4

Gear ratio to match

CurrentEquivalent
3.423.61
3.553.74
3.733.93
4.104.32

315/75R16 is 1.79" taller than 305/70R16, a +5.46% 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 0.90" (half the diameter change), and the tire needs 0.90" more room above it.

315/75R16 is 0.39" wider. On the same wheel offset about half of that, 0.20", moves toward the suspension and half toward the fender.

Both fit a 16" wheel; the sidewall is 0.90" taller on 315/75R16.

Details: 305/70R16 in inches · 315/75R16 in inches · change sizes in the calculator

FAQ

What is the difference between 305/70R16 and 315/75R16?

315/75R16 is 1.79" taller (+5.46%) and 0.39" wider than 305/70R16.

Will 315/75R16 change my speedometer?

Yes, by +5.46%. When the speedometer shows 60 mph you would be going 63.3 mph.

Can I replace 305/70R16 with 315/75R16?

It is a +5.5% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.