Tire size comparison
235/50R19 vs 255/45R19
255/45R19 is −0.8% shorter than 235/50R19: 28.0 in vs 28.3 in (−0.22 in), and 0.8 in wider. With 255/45R19 on a vehicle set up for 235/50R19, 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 (255/45R19 instead of 235/50R19) · 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
235/50R19 vs 255/45R19: full comparison
| 235/50R19 | 255/45R19 | Difference | |
|---|---|---|---|
| Overall diameter | 28.25 in | 28.04 in | −0.22 in (−0.8%) |
| Width | 9.25 in | 10.04 in | +0.79 in (+8.5%) |
| Sidewall height | 4.63 in | 4.52 in | −0.11 in |
| Circumference | 88.8 in | 88.1 in | −0.7 in |
| Revs per mile (nominal) | 714 | 719 | +6 |
| Wheel diameter | 19 in | 19 in | ±0 in |
| Diameter in mm | 718 | 712 | −6 mm |
Speedometer difference
Your speedometer is calibrated for 235/50R19. Fitted with 255/45R19, the actual speed is the reading × 28.04 ÷ 28.25.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 19.8 mph | −0.2 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 | 59.5 mph | −0.5 mph |
| 70 mph | 69.5 mph | −0.5 mph |
| 80 mph | 79.4 mph | −0.6 mph |
Real tires: published diameters
235/50R19: 28–28.6 in published by 7 makers; 255/45R19: 27.8–28.1 in published by 5 makers. Calculated figures assume a nominal tire; the exact difference between two specific tires depends on their models.
More about each size: 235/50R19 · 255/45R19
Related comparisons
FAQ
Which is bigger, 235/50R19 or 255/45R19?
255/45R19 is −0.8% shorter than 235/50R19: 28.0 in vs 28.3 in (−0.22 in).
How much will my speedometer be off with 255/45R19 instead of 235/50R19?
The speedometer is calibrated for 235/50R19. With 255/45R19 it shows 60 mph when you are doing 59.5 mph, and 70 mph at 69.5 mph (−0.8%). Your speedometer also has its own factory tolerance.
Can I replace 235/50R19 with 255/45R19?
The diameter difference is −0.8%. 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.