Tire size comparison
255/85R16 vs 285/75R16
285/75R16 is −0.7% shorter than 255/85R16: 32.8 in vs 33.1 in (−0.24 in), and 1.2 in wider. With 285/75R16 on a vehicle set up for 255/85R16, the speedometer shows 60 mph at an actual 59.6 mph. That is within the ±3% difference many shops use as a rule of thumb (not a manufacturer or legal limit).
Set up for: checking a replacement size (285/75R16 instead of 255/85R16) · Different situation?
Your current size
e.g. 265/70R17, 2657017 or 33x12.50R20
Where do I find my size?
It's on the tire sidewall, e.g. P265/70R17 115T, and on the tire placard sticker on the driver's door jamb (also in the owner's manual). The placard shows the size the vehicle came with; the sidewall shows what is fitted now. If they differ, use the placard as your starting point. Digits are enough here: 2657017 or 33125020.
Size you're considering
255/85R16 vs 285/75R16: full comparison
| 255/85R16 | 285/75R16 | Difference | |
|---|---|---|---|
| Overall diameter | 33.07 in | 32.83 in | −0.24 in (−0.7%) |
| Width | 10.04 in | 11.22 in | +1.18 in (+11.8%) |
| Sidewall height | 8.53 in | 8.42 in | −0.12 in |
| Circumference | 103.9 in | 103.1 in | −0.7 in |
| Revs per mile (nominal) | 610 | 614 | +4 |
| Wheel diameter | 16 in | 16 in | ±0 in |
| Diameter in mm | 840 | 834 | −6 mm |
Speedometer difference
Your speedometer is calibrated for 255/85R16. Fitted with 285/75R16, the actual speed is the reading × 32.83 ÷ 33.07.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.9 mph | −0.1 mph |
| 30 mph | 29.8 mph | −0.2 mph |
| 45 mph | 44.7 mph | −0.3 mph |
| 55 mph | 54.6 mph | −0.4 mph |
| 60 mph | 59.6 mph | −0.4 mph |
| 70 mph | 69.5 mph | −0.5 mph |
| 80 mph | 79.4 mph | −0.6 mph |
Real tires: published diameters
255/85R16: 33.1–33.4 in published by 2 makers; 285/75R16: 32.7–33.2 in published by 5 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 255/85R16 · 285/75R16
Related comparisons
FAQ
Which is bigger, 255/85R16 or 285/75R16?
285/75R16 is −0.7% shorter than 255/85R16: 32.8 in vs 33.1 in (−0.24 in).
How much will my speedometer be off with 285/75R16 instead of 255/85R16?
The speedometer is calibrated for 255/85R16. With 285/75R16 it shows 60 mph when you are doing 59.6 mph, and 70 mph at 69.5 mph (−0.7%). Your speedometer also has its own factory tolerance.
Can I replace 255/85R16 with 285/75R16?
The diameter difference is −0.7%. Whether it fits depends on things this calculation can't see: wheel width and offset, clearance at full lock and over bumps, load index and speed rating, and your vehicle maker's approval. Check your door-jamb placard and owner's manual and ask a tire professional.