Tire size comparison
175/65R15 vs 185/60R15
185/60R15 is −0.9% shorter than 175/65R15: 23.7 in vs 24.0 in (−0.22 in), and 0.4 in wider. With 185/60R15 on a vehicle set up for 175/65R15, the speedometer shows 60 mph at an actual 59.5 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 (185/60R15 instead of 175/65R15) · 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
175/65R15 vs 185/60R15: full comparison
| 175/65R15 | 185/60R15 | Difference | |
|---|---|---|---|
| Overall diameter | 23.96 in | 23.74 in | −0.22 in (−0.9%) |
| Width | 6.89 in | 7.28 in | +0.39 in (+5.7%) |
| Sidewall height | 4.48 in | 4.37 in | −0.11 in |
| Circumference | 75.3 in | 74.6 in | −0.7 in |
| Revs per mile (nominal) | 842 | 850 | +8 |
| Wheel diameter | 15 in | 15 in | ±0 in |
| Diameter in mm | 608 | 603 | −6 mm |
Speedometer difference
Your speedometer is calibrated for 175/65R15. Fitted with 185/60R15, the actual speed is the reading × 23.74 ÷ 23.96.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.8 mph | −0.2 mph |
| 30 mph | 29.7 mph | −0.3 mph |
| 45 mph | 44.6 mph | −0.4 mph |
| 55 mph | 54.5 mph | −0.5 mph |
| 60 mph | 59.5 mph | −0.5 mph |
| 70 mph | 69.4 mph | −0.6 mph |
| 80 mph | 79.3 mph | −0.7 mph |
Real tires: published diameters
175/65R15: 23.9–24.1 in published by 4 makers; 185/60R15: 23.6–23.9 in published by 4 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 175/65R15 · 185/60R15
Related comparisons
FAQ
Which is bigger, 175/65R15 or 185/60R15?
185/60R15 is −0.9% shorter than 175/65R15: 23.7 in vs 24.0 in (−0.22 in).
How much will my speedometer be off with 185/60R15 instead of 175/65R15?
The speedometer is calibrated for 175/65R15. With 185/60R15 it shows 60 mph when you are doing 59.5 mph, and 70 mph at 69.4 mph (−0.9%). Your speedometer also has its own factory tolerance.
Can I replace 175/65R15 with 185/60R15?
The diameter difference is −0.9%. 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.