235/75R15 vs 245/70R16
New overall diameter
29.50″
was 28.88″
True speed at an indicated 60
61.3 mph
your speedo reads low
Revolutions per mile
684
was 698, −15
| Measurement | 235/75R15 | 245/70R16 | Change |
|---|---|---|---|
| Overall diameter | 28.88″ | 29.50″ | +0.63″ (+2.2%) |
| Sidewall height | 6.94″ (176.3 mm) | 6.75″ (171.5 mm) | −4.8 mm |
| Tread width | 235 mm | 245 mm | +10 mm |
| Circumference | 90.72″ | 92.69″ | +1.97″ |
| Revs per mile | 698 | 684 | −15 |
| Speedometer error | baseline | +2.2% | reads low |
Diameter overlay
235/75R15 245/70R16
Speedometer check
With 245/70R16 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
25.5 mph actual
35 mph shown
35.8 mph actual
45 mph shown
46.0 mph actual
55 mph shown
56.2 mph actual
65 mph shown
66.4 mph actual
75 mph shown
76.6 mph actual
Common questions
- Will 245/70R16 fit instead of 235/75R15?
- Overall diameter changes 2.2%; section width changes 10 mm. Diameter comparison alone cannot confirm fitment. Verify the vehicle maker's approved rim width, tire load and speed ratings, and clearance at full steering lock and suspension compression. Confirm any possible ABS, traction-control, speedometer, and drivetrain effects with the vehicle maker or a qualified tire professional. Overall diameter goes from 28.88″ to 29.50″, a change of +2.2%. 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 245/70R16?
- At an indicated 60 mph you are really doing about 61.3 mph, a +2.2% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 235/75R15 and 245/70R16?
- 235/75R15 turns about 698 times per mile and 245/70R16 turns about 684, a difference of −15. Your speedometer and odometer both count rotations, so this number is what throws them off.