235/70R16 vs 245/75R16
Switching from 235/70R16 to 245/75R16 changes the overall diameter by +38.5 mm (+5.2%) — outside the commonly used ±3% guideline. Every figure below is calculated from the two size codes with the standard formulas.
| Measurement | 235/70R16 | 245/75R16 | Difference |
|---|---|---|---|
| Overall diameter | 735.4 mm | 773.9 mm | +38.5 mm (+5.2%) |
| Overall diameter | 28.95 in | 30.47 in | +1.52 in |
| Tire width | 235 mm (9.25 in) | 245 mm (9.65 in) | +10 mm |
| Sidewall height | 164.5 mm (6.48 in) | 183.8 mm (7.23 in) | +19.3 mm |
| Wheel (rim) diameter | 16.0 in | 16.0 in | 0.0 in |
| Circumference | 2310 mm | 2431 mm | +121 mm |
| Revolutions per mile | 2188 | 2080 | -109 |
| Revolutions per km | 433 | 411 | -22 |
Speedometer error
Calibrated for 235/70R16, the speedometer under-reads or over-reads once 245/75R16 is fitted. This is your real speed at each indicated speed:
| Speedometer shows | Actual speed on 245/75R16 | Error |
|---|---|---|
| 20 mph | 21.0 mph | +1.0 mph |
| 40 mph | 42.1 mph | +2.1 mph |
| 60 mph | 63.1 mph | +3.1 mph |
| 80 mph | 84.2 mph | +4.2 mph |
| 100 mph | 105.2 mph | +5.2 mph |
How these two sizes are worked out
235/70R16 breaks down as a 235 mm tread width with a sidewall of 70% of that width (164.5 mm) on a 16.0-inch wheel, giving an overall diameter of 735.4 mm (28.95 in). 245/75R16 works out to 773.9 mm (30.47 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 235/70R16 tires with 245/75R16?
The diameter change is +5.2%, which is outside 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 245/75R16 make my speedometer read wrong?
Yes, by the diameter ratio. When the dial shows 60 mph you are really doing 63.1 mph on 245/75R16. The full table above covers 20 to 100 mph.
Which tire is taller, 235/70R16 or 245/75R16?
245/75R16 is taller — 773.9 mm against 735.4 mm overall diameter, a difference of 38.5 mm.