Tire size comparison
225/40R19 vs 255/35R19
255/35R19 is −0.2% shorter than 225/40R19: 26.0 in vs 26.1 in (−0.06 in), and 1.2 in wider. With 255/35R19 on a vehicle set up for 225/40R19, the speedometer shows 60 mph at an actual 59.9 mph. That is within the ±3% difference many shops use as a rule of thumb (not a manufacturer or legal limit).
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). If your current tires aren't the original size, the placard shows what the vehicle came with. Digits are enough here: 2657017 or 33125020.
Size you're considering
225/40R19 vs 255/35R19: full comparison
| 225/40R19 | 255/35R19 | Difference | |
|---|---|---|---|
| Overall diameter | 26.09 in | 26.03 in | −0.06 in (−0.2%) |
| Width | 8.86 in | 10.04 in | +1.18 in (+13.3%) |
| Sidewall height | 3.54 in | 3.51 in | −0.03 in |
| Circumference | 82.0 in | 81.8 in | −0.2 in |
| Revs per mile (nominal) | 773 | 775 | +2 |
| Wheel diameter | 19 in | 19 in | ±0 in |
| Diameter in mm | 663 | 661 | −2 mm |
Speedometer difference
Your speedometer is calibrated for 225/40R19. Fitted with 255/35R19, the actual speed is the reading × 26.03 ÷ 26.09.
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.0 mph | ±0.0 mph |
| 30 mph | 29.9 mph | −0.1 mph |
| 45 mph | 44.9 mph | −0.1 mph |
| 55 mph | 54.9 mph | −0.1 mph |
| 60 mph | 59.9 mph | −0.1 mph |
| 70 mph | 69.8 mph | −0.2 mph |
| 80 mph | 79.8 mph | −0.2 mph |
Real tires: published diameters
225/40R19: 25.8–26.3 in published by 6 makers; 255/35R19: 25.8–26.1 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: 225/40R19 · 255/35R19
Related comparisons
FAQ
Which is bigger, 225/40R19 or 255/35R19?
255/35R19 is −0.2% shorter than 225/40R19: 26.0 in vs 26.1 in (−0.06 in).
How much will my speedometer be off with 255/35R19 instead of 225/40R19?
The speedometer is calibrated for 225/40R19. With 255/35R19 it shows 60 mph when you are doing 59.9 mph, and 70 mph at 69.8 mph (−0.2%). Your speedometer also has its own factory tolerance.
Can I replace 225/40R19 with 255/35R19?
The diameter difference is −0.2%. 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.