285/35R19 vs 305/30R19

285/35R19 is 0.6" taller than 305/30R19 (2.4%)

Diameter difference−2.42%diameter 26.85" → 26.20"
285/35R19305/30R19
285/35R19305/30R19Difference
Overall diameter26.85"26.20"−0.65"
Section width11.22"12.01"+0.79"
Sidewall height3.93"3.60"−0.32"
Circumference84.4"82.3"−2.0"
Revolutions per mile751770+19
Wheel diameter19"19"±0"

Speedometer

ShowsActualDiff
30 mph29.3 mph−0.7
45 mph43.9 mph−1.1
60 mph58.5 mph−1.5
70 mph68.3 mph−1.7
80 mph78.1 mph−1.9

Gear ratio to match

CurrentEquivalent
3.423.34
3.553.46
3.733.64
4.104.00

305/30R19 is 0.65" shorter than 285/35R19, a −2.42% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.32" (half the diameter change), and the tire needs 0.32" less room above it.

305/30R19 is 0.79" wider. On the same wheel offset about half of that, 0.39", moves toward the suspension and half toward the fender.

Both fit a 19" wheel; the sidewall is 0.32" shorter on 305/30R19.

Details: 285/35R19 in inches · 305/30R19 in inches · change sizes in the calculator

FAQ

What is the difference between 285/35R19 and 305/30R19?

305/30R19 is 0.65" shorter (−2.42%) and 0.79" wider than 285/35R19.

Will 305/30R19 change my speedometer?

Yes, by −2.42%. When the speedometer shows 60 mph you would be going 58.5 mph.

Can I replace 285/35R19 with 305/30R19?

Often yes: the diameter change of −2.4% is within the common 3% guideline. Check the load index, speed rating and clearance.