305/75R16 vs 315/75R16

315/75R16 is 0.6" taller than 305/75R16 (1.7%)

Diameter difference+1.74%diameter 34.01" → 34.60"
305/75R16315/75R16
305/75R16315/75R16Difference
Overall diameter34.01"34.60"+0.59"
Section width12.01"12.40"+0.39"
Sidewall height9.01"9.30"+0.30"
Circumference106.9"108.7"+1.9"
Revolutions per mile593583−10
Wheel diameter16"16"±0"

Speedometer

ShowsActualDiff
30 mph30.5 mph+0.5
45 mph45.8 mph+0.8
60 mph61.0 mph+1.0
70 mph71.2 mph+1.2
80 mph81.4 mph+1.4

Gear ratio to match

CurrentEquivalent
3.423.48
3.553.61
3.733.79
4.104.17

315/75R16 is 0.59" taller than 305/75R16, a +1.74% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.30" (half the diameter change), and the tire needs 0.30" 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 0.30" taller on 315/75R16.

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

FAQ

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

315/75R16 is 0.59" taller (+1.74%) and 0.39" wider than 305/75R16.

Will 315/75R16 change my speedometer?

Yes, by +1.74%. When the speedometer shows 60 mph you would be going 61.0 mph.

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

Often yes: the diameter change of +1.7% is within the common 3% guideline. Check the load index, speed rating and clearance.