Tire size comparison
225/45R17 vs 235/45R17
235/45R17 is +1.4% taller than 225/45R17: 25.3 in vs 25.0 in (+0.35 in), and 0.4 in wider. With 235/45R17 on a vehicle set up for 225/45R17, the speedometer shows 60 mph at an actual 60.9 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 (235/45R17 instead of 225/45R17) · 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
225/45R17 vs 235/45R17: full comparison
| 225/45R17 | 235/45R17 | Difference | |
|---|---|---|---|
| Overall diameter | 24.97 in | 25.33 in | +0.35 in (+1.4%) |
| Width | 8.86 in | 9.25 in | +0.39 in (+4.4%) |
| Sidewall height | 3.99 in | 4.16 in | +0.18 in |
| Circumference | 78.5 in | 79.6 in | +1.1 in |
| Revs per mile (nominal) | 808 | 796 | −11 |
| Wheel diameter | 17 in | 17 in | ±0 in |
| Diameter in mm | 634 | 643 | +9 mm |
Speedometer difference
Your speedometer is calibrated for 225/45R17. Fitted with 235/45R17, the actual speed is the reading × 25.33 ÷ 24.97.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.3 mph | +0.3 mph |
| 30 mph | 30.4 mph | +0.4 mph |
| 45 mph | 45.6 mph | +0.6 mph |
| 55 mph | 55.8 mph | +0.8 mph |
| 60 mph | 60.9 mph | +0.9 mph |
| 70 mph | 71.0 mph | +1.0 mph |
| 80 mph | 81.1 mph | +1.1 mph |
Real tires: published diameters
225/45R17: 24.7–25.2 in published by 6 makers; 235/45R17: 25.1–25.6 in published by 7 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 225/45R17 · 235/45R17
Related comparisons
FAQ
Which is bigger, 225/45R17 or 235/45R17?
235/45R17 is +1.4% taller than 225/45R17: 25.3 in vs 25.0 in (+0.35 in).
How much will my speedometer be off with 235/45R17 instead of 225/45R17?
The speedometer is calibrated for 225/45R17. With 235/45R17 it shows 60 mph when you are doing 60.9 mph, and 70 mph at 71.0 mph (+1.4%). Your speedometer also has its own factory tolerance.
Can I replace 225/45R17 with 235/45R17?
The diameter difference is +1.4%. 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.