285/70R17 vs 33x12.50R17 — Tire Size Comparison
A 33x12.50R17 is 33" tall and 12.5" wide. A 285/70R17 is 32.71" tall and 11.22" wide. The 33x12.50R17 is +0.29" (+0.89%) in diameter, adds about 0.15" of ride height, and at an indicated 60 mph your actual speed becomes about 60.5 mph.
Current tire on your vehicle now
New tire you are considering
Full comparison
| Measurement | 285/70R17 | 33x12.50R17 | Difference |
|---|---|---|---|
| Overall diameter | 32.71" | 33" | +0.29" (+0.89%) |
| Width | 11.22" | 12.5" | +1.28" |
| Sidewall height | 7.85" | 8" | +0.15" |
| Circumference | 102.8" | 103.7" | +0.9" |
| Revolutions / mile | 617 | 611 | -6 |
| Ride height change | — | — | +0.15" |
Speedometer effect
Assuming your speedometer was accurate on the current tire, here is what changes. Bigger tires make the speedometer read low — you travel faster than it shows.
| Speedometer shows | 20 mph | 30 mph | 40 mph | 50 mph | 60 mph | 70 mph | 80 mph |
|---|---|---|---|---|---|---|---|
| Actual speed | 20.2 | 30.3 | 40.4 | 50.4 | 60.5 | 70.6 | 80.7 |
Before you buy: fitment checklist
- Wheel diameter: SAME RIM Both sizes fit a 17" wheel — no new wheels needed for diameter.
- Diameter change: DIAMETER Diameter changes 0.89% — within the ±3% range installers commonly use as a rule of thumb. That rule is a guideline, not a safety standard.
- Clearance: WIDTH The new tire is 33 mm wider — check inner clearance at full steering lock and full suspension travel.
- Rim width: CHECK Confirm the new size's approved rim-width range (from the tire maker) includes your wheel's width.
- Load & speed: CHECK The new tire's load index and speed rating must meet or exceed your vehicle's placard (driver's door jamb).
This is a size comparison, not a fitment guarantee. Clearance depends on your vehicle's suspension, wheel offset and alignment — the checklist above covers what to verify.
More comparisons with these sizes
How much bigger is a 33x12.50R17 than a 285/70R17?
Taller by 0.29" in diameter (0.89%), 1.28" wider, with a 0.15" taller sidewall. Revolutions per mile go from 617 to 611.
Can I switch from 285/70R17 to 33x12.50R17 on the same wheels?
Both sizes mount on a 17" wheel, so the wheel diameter matches. You still need your wheel's width inside the 33x12.50R17's approved rim-width range, a load index and speed rating at least equal to your door-jamb placard, and clearance at full lock — see the checklist above.
Will the speedometer be off?
Yes, by about 0.89%. At an indicated 60 mph you are actually doing about 60.5 mph on the 33x12.50R17.
Nominal geometry — method. Last verified November 12, 2026.