Tire size comparison
255/45R19 vs 255/50R19
255/50R19 is +3.6% taller than 255/45R19: 29.0 in vs 28.0 in (+1.00 in), and the same width. With 255/50R19 on a vehicle set up for 255/45R19, the speedometer shows 60 mph at an actual 62.1 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 (255/50R19 instead of 255/45R19) · 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
255/45R19 vs 255/50R19: full comparison
| 255/45R19 | 255/50R19 | Difference | |
|---|---|---|---|
| Overall diameter | 28.04 in | 29.04 in | +1.00 in (+3.6%) |
| Width | 10.04 in | 10.04 in | ±0.00 in (±0.0%) |
| Sidewall height | 4.52 in | 5.02 in | +0.50 in |
| Circumference | 88.1 in | 91.2 in | +3.2 in |
| Revs per mile (nominal) | 719 | 695 | −25 |
| Wheel diameter | 19 in | 19 in | ±0 in |
| Diameter in mm | 712 | 738 | +26 mm |
Speedometer difference
Your speedometer is calibrated for 255/45R19. Fitted with 255/50R19, the actual speed is the reading × 29.04 ÷ 28.04.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.7 mph | +0.7 mph |
| 30 mph | 31.1 mph | +1.1 mph |
| 45 mph | 46.6 mph | +1.6 mph |
| 55 mph | 57.0 mph | +2.0 mph |
| 60 mph | 62.1 mph | +2.1 mph |
| 70 mph | 72.5 mph | +2.5 mph |
| 80 mph | 82.9 mph | +2.9 mph |
Real tires: published diameters
255/45R19: 27.8–28.1 in published by 5 makers; 255/50R19: 28.8–29.4 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: 255/45R19 · 255/50R19
Related comparisons
FAQ
Which is bigger, 255/45R19 or 255/50R19?
255/50R19 is +3.6% taller than 255/45R19: 29.0 in vs 28.0 in (+1.00 in).
How much will my speedometer be off with 255/50R19 instead of 255/45R19?
The speedometer is calibrated for 255/45R19. With 255/50R19 it shows 60 mph when you are doing 62.1 mph, and 70 mph at 72.5 mph (+3.6%). Your speedometer also has its own factory tolerance.
Can I replace 255/45R19 with 255/50R19?
The diameter difference is +3.6%. 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.