285/40R24 vs 305/35R24

285/40R24 is 0.6" taller than 305/35R24 (1.7%)

Diameter difference−1.73%diameter 32.98" → 32.41"
285/40R24305/35R24
285/40R24305/35R24Difference
Overall diameter32.98"32.41"−0.57"
Section width11.22"12.01"+0.79"
Sidewall height4.49"4.20"−0.29"
Circumference103.6"101.8"−1.8"
Revolutions per mile612622+11
Wheel diameter24"24"±0"

Speedometer

ShowsActualDiff
30 mph29.5 mph−0.5
45 mph44.2 mph−0.8
60 mph59.0 mph−1.0
70 mph68.8 mph−1.2
80 mph78.6 mph−1.4

Gear ratio to match

CurrentEquivalent
3.423.36
3.553.49
3.733.67
4.104.03

305/35R24 is 0.57" shorter than 285/40R24, a −1.73% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.29" (half the diameter change), and the tire needs 0.29" less room above it.

305/35R24 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 24" wheel; the sidewall is 0.29" shorter on 305/35R24.

Details: 285/40R24 in inches · 305/35R24 in inches · change sizes in the calculator

FAQ

What is the difference between 285/40R24 and 305/35R24?

305/35R24 is 0.57" shorter (−1.73%) and 0.79" wider than 285/40R24.

Will 305/35R24 change my speedometer?

Yes, by −1.73%. When the speedometer shows 60 mph you would be going 59.0 mph.

Can I replace 285/40R24 with 305/35R24?

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