Tire size comparison
295/70R17 vs 285/70R17
285/70R17 is −1.7% shorter than 295/70R17: 32.7 in vs 33.3 in (−0.55 in), and 0.4 in narrower. With 285/70R17 on a vehicle set up for 295/70R17, the speedometer shows 60 mph at an actual 59.0 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 (285/70R17 instead of 295/70R17) · 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
295/70R17 vs 285/70R17: full comparison
| 295/70R17 | 285/70R17 | Difference | |
|---|---|---|---|
| Overall diameter | 33.26 in | 32.71 in | −0.55 in (−1.7%) |
| Width | 11.61 in | 11.22 in | −0.39 in (−3.4%) |
| Sidewall height | 8.13 in | 7.85 in | −0.28 in |
| Circumference | 104.5 in | 102.8 in | −1.7 in |
| Revs per mile (nominal) | 606 | 617 | +10 |
| Wheel diameter | 17 in | 17 in | ±0 in |
| Diameter in mm | 845 | 831 | −14 mm |
Speedometer difference
Your speedometer is calibrated for 295/70R17. Fitted with 285/70R17, the actual speed is the reading × 32.71 ÷ 33.26.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.7 mph | −0.3 mph |
| 30 mph | 29.5 mph | −0.5 mph |
| 45 mph | 44.3 mph | −0.7 mph |
| 55 mph | 54.1 mph | −0.9 mph |
| 60 mph | 59.0 mph | −1.0 mph |
| 70 mph | 68.8 mph | −1.2 mph |
| 80 mph | 78.7 mph | −1.3 mph |
Real tires: published diameters
295/70R17: 33.2–33.54 in published by 5 makers; 285/70R17: 32.7–33.15 in published by 6 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 295/70R17 · 285/70R17
Related comparisons
FAQ
Which is bigger, 295/70R17 or 285/70R17?
285/70R17 is −1.7% shorter than 295/70R17: 32.7 in vs 33.3 in (−0.55 in).
How much will my speedometer be off with 285/70R17 instead of 295/70R17?
The speedometer is calibrated for 295/70R17. With 285/70R17 it shows 60 mph when you are doing 59.0 mph, and 70 mph at 68.8 mph (−1.7%). Your speedometer also has its own factory tolerance.
Can I replace 295/70R17 with 285/70R17?
The diameter difference is −1.7%. 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.