Tire size comparison
175/70R14 vs 185/65R14
185/65R14 is −0.7% shorter than 175/70R14: 23.5 in vs 23.6 in (−0.18 in), and 0.4 in wider. With 185/65R14 on a vehicle set up for 175/70R14, 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 (185/65R14 instead of 175/70R14) · 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
175/70R14 vs 185/65R14: full comparison
| 175/70R14 | 185/65R14 | Difference | |
|---|---|---|---|
| Overall diameter | 23.65 in | 23.47 in | −0.18 in (−0.7%) |
| Width | 6.89 in | 7.28 in | +0.39 in (+5.7%) |
| Sidewall height | 4.82 in | 4.73 in | −0.09 in |
| Circumference | 74.3 in | 73.7 in | −0.6 in |
| Revs per mile (nominal) | 853 | 859 | +6 |
| Wheel diameter | 14 in | 14 in | ±0 in |
| Diameter in mm | 601 | 596 | −4 mm |
Speedometer difference
Your speedometer is calibrated for 175/70R14. Fitted with 185/65R14, the actual speed is the reading × 23.47 ÷ 23.65.
| 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
175/70R14: 23.6–23.7 in published by 2 makers; 185/65R14: 23.3–23.5 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: 175/70R14 · 185/65R14
Related comparisons
FAQ
Which is bigger, 175/70R14 or 185/65R14?
185/65R14 is −0.7% shorter than 175/70R14: 23.5 in vs 23.6 in (−0.18 in).
How much will my speedometer be off with 185/65R14 instead of 175/70R14?
The speedometer is calibrated for 175/70R14. With 185/65R14 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 175/70R14 with 185/65R14?
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.