255/40R19 vs 275/35R19
Switching from 255/40R19 to 275/35R19 changes the overall diameter by -11.5 mm (-1.7%) — inside the commonly used ±3% guideline. Every figure below is calculated from the two size codes with the standard formulas.
| Measurement | 255/40R19 | 275/35R19 | Difference |
|---|---|---|---|
| Overall diameter | 686.6 mm | 675.1 mm | -11.5 mm (-1.7%) |
| Overall diameter | 27.03 in | 26.58 in | -0.45 in |
| Tire width | 255 mm (10.04 in) | 275 mm (10.83 in) | +20 mm |
| Sidewall height | 102.0 mm (4.02 in) | 96.3 mm (3.79 in) | -5.8 mm |
| Wheel (rim) diameter | 19.0 in | 19.0 in | 0.0 in |
| Circumference | 2157 mm | 2121 mm | -36 mm |
| Revolutions per mile | 2344 | 2384 | +40 |
| Revolutions per km | 464 | 472 | +8 |
Speedometer error
Calibrated for 255/40R19, the speedometer under-reads or over-reads once 275/35R19 is fitted. This is your real speed at each indicated speed:
| Speedometer shows | Actual speed on 275/35R19 | Error |
|---|---|---|
| 20 mph | 19.7 mph | -0.3 mph |
| 40 mph | 39.3 mph | -0.7 mph |
| 60 mph | 59.0 mph | -1.0 mph |
| 80 mph | 78.7 mph | -1.3 mph |
| 100 mph | 98.3 mph | -1.7 mph |
How these two sizes are worked out
255/40R19 breaks down as a 255 mm tread width with a sidewall of 40% of that width (102.0 mm) on a 19.0-inch wheel, giving an overall diameter of 686.6 mm (27.03 in). 275/35R19 works out to 675.1 mm (26.58 in) the same way. The standard formulas are the same ones used on the tire size calculator page: diameter = rim × 25.4 + 2 × sidewall, circumference = π × diameter, revolutions per mile = 63,360 ÷ diameter in inches.
Nominal sizes vary slightly between brands and models, and tread wear shrinks a tire over its life. These figures follow the size codes exactly; your vehicle manual or a professional tire shop is the authority for what fits your vehicle.
More comparisons
Frequently asked questions
Can I replace 255/40R19 tires with 275/35R19?
The diameter change is -1.7%, which is within the commonly used ±3% guideline. Diameter is only one part of fitment — wheel width range, load index, speed rating and physical clearance all have to check out too, so confirm with your vehicle manual or a professional tire shop before buying.
Will 275/35R19 make my speedometer read wrong?
Yes, by the diameter ratio. When the dial shows 60 mph you are really doing 59.0 mph on 275/35R19. The full table above covers 20 to 100 mph.
Which tire is taller, 255/40R19 or 275/35R19?
255/40R19 is taller — 686.6 mm against 675.1 mm overall diameter, a difference of 11.5 mm.