235/70R16 vs 245/75R16
New overall diameter
30.47″
was 28.95″
True speed at an indicated 60
63.1 mph
your speedo reads low
Revolutions per mile
662
was 697, −35
| Measurement | 235/70R16 | 245/75R16 | Change |
|---|---|---|---|
| Overall diameter | 28.95″ | 30.47″ | +1.52″ (+5.2%) |
| Sidewall height | 6.48″ (164.5 mm) | 7.23″ (183.8 mm) | +19.3 mm |
| Tread width | 235 mm | 245 mm | +10 mm |
| Circumference | 90.96″ | 95.72″ | +4.76″ |
| Revs per mile | 697 | 662 | −35 |
| Speedometer error | baseline | +5.2% | reads low |
Diameter overlay
235/70R16 245/75R16
Speedometer check
With 245/75R16 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
26.3 mph actual
35 mph shown
36.8 mph actual
45 mph shown
47.4 mph actual
55 mph shown
57.9 mph actual
65 mph shown
68.4 mph actual
75 mph shown
78.9 mph actual
Common questions
- Will 245/75R16 fit instead of 235/70R16?
- 5.2% is past the 5% mark, which is where this stops being a tire choice and starts being a project. Expect rubbing, meaningful speedometer error, and extra load on ABS, stability control and the drivetrain. Recalibration is the usual fix. Your speedometer will read low, so you are going faster than it says. Overall diameter goes from 28.95″ to 30.47″, a change of +5.2%. The rule of thumb most shops use: under 3% is fine, 3 to 5% needs a clearance check, over 5% needs recalibration.
- How far off will my speedometer read on 245/75R16?
- At an indicated 60 mph you are really doing about 63.1 mph, a +5.2% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 235/70R16 and 245/75R16?
- 235/70R16 turns about 697 times per mile and 245/75R16 turns about 662, a difference of −35. Your speedometer and odometer both count rotations, so this number is what throws them off.