255/70R16 vs 265/70R16
Switching from 255/70R16 to 265/70R16 changes the overall diameter by +14.0 mm (+1.8%) — inside the commonly used ±3% guideline. Every figure below is calculated from the two size codes with the standard formulas.
| Measurement | 255/70R16 | 265/70R16 | Difference |
|---|---|---|---|
| Overall diameter | 763.4 mm | 777.4 mm | +14.0 mm (+1.8%) |
| Overall diameter | 30.06 in | 30.61 in | +0.55 in |
| Tire width | 255 mm (10.04 in) | 265 mm (10.43 in) | +10 mm |
| Sidewall height | 178.5 mm (7.03 in) | 185.5 mm (7.30 in) | +7.0 mm |
| Wheel (rim) diameter | 16.0 in | 16.0 in | 0.0 in |
| Circumference | 2398 mm | 2442 mm | +44 mm |
| Revolutions per mile | 2108 | 2070 | -38 |
| Revolutions per km | 417 | 409 | -8 |
Speedometer error
Calibrated for 255/70R16, the speedometer under-reads or over-reads once 265/70R16 is fitted. This is your real speed at each indicated speed:
| Speedometer shows | Actual speed on 265/70R16 | Error |
|---|---|---|
| 20 mph | 20.4 mph | +0.4 mph |
| 40 mph | 40.7 mph | +0.7 mph |
| 60 mph | 61.1 mph | +1.1 mph |
| 80 mph | 81.5 mph | +1.5 mph |
| 100 mph | 101.8 mph | +1.8 mph |
How these two sizes are worked out
255/70R16 breaks down as a 255 mm tread width with a sidewall of 70% of that width (178.5 mm) on a 16.0-inch wheel, giving an overall diameter of 763.4 mm (30.06 in). 265/70R16 works out to 777.4 mm (30.61 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 255/70R16 tires with 265/70R16?
The diameter change is +1.8%, 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 265/70R16 make my speedometer read wrong?
Yes, by the diameter ratio. When the dial shows 60 mph you are really doing 61.1 mph on 265/70R16. The full table above covers 20 to 100 mph.
Which tire is taller, 255/70R16 or 265/70R16?
265/70R16 is taller — 777.4 mm against 763.4 mm overall diameter, a difference of 14.0 mm.