Tire size comparison
185/65R14 vs 185/70R14
185/70R14 is +3.1% taller than 185/65R14: 24.2 in vs 23.5 in (+0.73 in), and the same width. With 185/70R14 on a vehicle set up for 185/65R14, the speedometer shows 60 mph at an actual 61.9 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 bigger (185/70R14 instead of 185/65R14) · 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
185/65R14 vs 185/70R14: full comparison
| 185/65R14 | 185/70R14 | Difference | |
|---|---|---|---|
| Overall diameter | 23.47 in | 24.20 in | +0.73 in (+3.1%) |
| Width | 7.28 in | 7.28 in | ±0.00 in (±0.0%) |
| Sidewall height | 4.73 in | 5.10 in | +0.36 in |
| Circumference | 73.7 in | 76.0 in | +2.3 in |
| Revs per mile (nominal) | 859 | 834 | −26 |
| Wheel diameter | 14 in | 14 in | ±0 in |
| Diameter in mm | 596 | 615 | +18 mm |
Speedometer difference
Your speedometer is calibrated for 185/65R14. Fitted with 185/70R14, the actual speed is the reading × 24.20 ÷ 23.47.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.6 mph | +0.6 mph |
| 30 mph | 30.9 mph | +0.9 mph |
| 45 mph | 46.4 mph | +1.4 mph |
| 55 mph | 56.7 mph | +1.7 mph |
| 60 mph | 61.9 mph | +1.9 mph |
| 70 mph | 72.2 mph | +2.2 mph |
| 80 mph | 82.5 mph | +2.5 mph |
Real tires: published diameters
185/65R14: 23.3–23.5 in published by 4 makers; 185/70R14: 24.1–24.3 in published by 3 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 185/65R14 · 185/70R14
Related comparisons
FAQ
Which is bigger, 185/65R14 or 185/70R14?
185/70R14 is +3.1% taller than 185/65R14: 24.2 in vs 23.5 in (+0.73 in).
How much will my speedometer be off with 185/70R14 instead of 185/65R14?
The speedometer is calibrated for 185/65R14. With 185/70R14 it shows 60 mph when you are doing 61.9 mph, and 70 mph at 72.2 mph (+3.1%). Your speedometer also has its own factory tolerance.
Can I replace 185/65R14 with 185/70R14?
The diameter difference is +3.1%. 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.