225/45R18 vs 215/60R16
New overall diameter
26.16″
was 25.97″
True speed at an indicated 60
60.4 mph
your speedo reads low
Revolutions per mile
771
was 777, −5
| Measurement | 225/45R18 | 215/60R16 | Change |
|---|---|---|---|
| Overall diameter | 25.97″ | 26.16″ | +0.19″ (+0.7%) |
| Sidewall height | 3.99″ (101.3 mm) | 5.08″ (129.0 mm) | +27.8 mm |
| Tread width | 225 mm | 215 mm | −10 mm |
| Circumference | 81.59″ | 82.18″ | +0.58″ |
| Revs per mile | 777 | 771 | −5 |
| Speedometer error | baseline | +0.7% | reads low |
Diameter overlay
225/45R18 215/60R16
Speedometer check
With 215/60R16 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
25.2 mph actual
35 mph shown
35.2 mph actual
45 mph shown
45.3 mph actual
55 mph shown
55.4 mph actual
65 mph shown
65.5 mph actual
75 mph shown
75.5 mph actual
Common questions
- Will 215/60R16 fit instead of 225/45R18?
- Overall diameter changes 0.7%; 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 25.97″ to 26.16″, a change of +0.7%. 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 215/60R16?
- At an indicated 60 mph you are really doing about 60.4 mph, a +0.7% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 225/45R18 and 215/60R16?
- 225/45R18 turns about 777 times per mile and 215/60R16 turns about 771, a difference of −5. Your speedometer and odometer both count rotations, so this number is what throws them off.