Tire size comparison
255/70R15 vs 275/60R15
275/60R15 is −3.7% shorter than 255/70R15: 28.0 in vs 29.1 in (−1.06 in), and 0.8 in wider. With 275/60R15 on a vehicle set up for 255/70R15, the speedometer shows 60 mph at an actual 57.8 mph. That is more than the ±3% difference many shops use as a rule of thumb, so check carefully before switching.
Set up for: going smaller (275/60R15 instead of 255/70R15) · 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
255/70R15 vs 275/60R15: full comparison
| 255/70R15 | 275/60R15 | Difference | |
|---|---|---|---|
| Overall diameter | 29.06 in | 27.99 in | −1.06 in (−3.7%) |
| Width | 10.04 in | 10.83 in | +0.79 in (+7.8%) |
| Sidewall height | 7.03 in | 6.50 in | −0.53 in |
| Circumference | 91.3 in | 87.9 in | −3.3 in |
| Revs per mile (nominal) | 694 | 720 | +26 |
| Wheel diameter | 15 in | 15 in | ±0 in |
| Diameter in mm | 738 | 711 | −27 mm |
Speedometer difference
Your speedometer is calibrated for 255/70R15. Fitted with 275/60R15, the actual speed is the reading × 27.99 ÷ 29.06.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.3 mph | −0.7 mph |
| 30 mph | 28.9 mph | −1.1 mph |
| 45 mph | 43.4 mph | −1.6 mph |
| 55 mph | 53.0 mph | −2.0 mph |
| 60 mph | 57.8 mph | −2.2 mph |
| 70 mph | 67.4 mph | −2.6 mph |
| 80 mph | 77.1 mph | −2.9 mph |
Real tires: published diameters
255/70R15: 29 in published by 1 maker; 275/60R15: 27.9–27.99 in published by 2 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 255/70R15 · 275/60R15
Related comparisons
FAQ
Which is bigger, 255/70R15 or 275/60R15?
275/60R15 is −3.7% shorter than 255/70R15: 28.0 in vs 29.1 in (−1.06 in).
How much will my speedometer be off with 275/60R15 instead of 255/70R15?
The speedometer is calibrated for 255/70R15. With 275/60R15 it shows 60 mph when you are doing 57.8 mph, and 70 mph at 67.4 mph (−3.7%). Your speedometer also has its own factory tolerance.
Can I replace 255/70R15 with 275/60R15?
The diameter difference is −3.7%. 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.