Tire size comparison
205/45R17 vs 215/40R17
215/40R17 is −2.0% shorter than 205/45R17: 23.8 in vs 24.3 in (−0.49 in), and 0.4 in wider. With 215/40R17 on a vehicle set up for 205/45R17, the speedometer shows 60 mph at an actual 58.8 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 (215/40R17 instead of 205/45R17) · 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
205/45R17 vs 215/40R17: full comparison
| 205/45R17 | 215/40R17 | Difference | |
|---|---|---|---|
| Overall diameter | 24.26 in | 23.77 in | −0.49 in (−2.0%) |
| Width | 8.07 in | 8.46 in | +0.39 in (+4.9%) |
| Sidewall height | 3.63 in | 3.39 in | −0.25 in |
| Circumference | 76.2 in | 74.7 in | −1.5 in |
| Revs per mile (nominal) | 831 | 848 | +17 |
| Wheel diameter | 17 in | 17 in | ±0 in |
| Diameter in mm | 616 | 604 | −12 mm |
Speedometer difference
Your speedometer is calibrated for 205/45R17. Fitted with 215/40R17, the actual speed is the reading × 23.77 ÷ 24.26.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.6 mph | −0.4 mph |
| 30 mph | 29.4 mph | −0.6 mph |
| 45 mph | 44.1 mph | −0.9 mph |
| 55 mph | 53.9 mph | −1.1 mph |
| 60 mph | 58.8 mph | −1.2 mph |
| 70 mph | 68.6 mph | −1.4 mph |
| 80 mph | 78.4 mph | −1.6 mph |
Real tires: published diameters
205/45R17: 24–24.4 in published by 6 makers; 215/40R17: 23.8–23.9 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: 205/45R17 · 215/40R17
Related comparisons
FAQ
Which is bigger, 205/45R17 or 215/40R17?
215/40R17 is −2.0% shorter than 205/45R17: 23.8 in vs 24.3 in (−0.49 in).
How much will my speedometer be off with 215/40R17 instead of 205/45R17?
The speedometer is calibrated for 205/45R17. With 215/40R17 it shows 60 mph when you are doing 58.8 mph, and 70 mph at 68.6 mph (−2.0%). Your speedometer also has its own factory tolerance.
Can I replace 205/45R17 with 215/40R17?
The diameter difference is −2.0%. 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.