265/55R19 vs 265/50R20
New overall diameter
30.43″
was 30.48″
True speed at an indicated 60
59.9 mph
your speedo reads high
Revolutions per mile
663
was 662, +1
| Measurement | 265/55R19 | 265/50R20 | Change |
|---|---|---|---|
| Overall diameter | 30.48″ | 30.43″ | −0.04″ (−0.1%) |
| Sidewall height | 5.74″ (145.8 mm) | 5.22″ (132.5 mm) | −13.3 mm |
| Tread width | 265 mm | 265 mm | +0 mm |
| Circumference | 95.74″ | 95.61″ | −0.14″ |
| Revs per mile | 662 | 663 | +1 |
| Speedometer error | baseline | −0.1% | reads high |
Diameter overlay
265/55R19 265/50R20
Speedometer check
With 265/50R20 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
25.0 mph actual
35 mph shown
35.0 mph actual
45 mph shown
44.9 mph actual
55 mph shown
54.9 mph actual
65 mph shown
64.9 mph actual
75 mph shown
74.9 mph actual
Common questions
- Will 265/50R20 fit instead of 265/55R19?
- Diameter moves 0.1%, comfortably inside the 3% rule. Your speedometer, ABS, traction control and gearing all stay in the range they were calibrated for. Your speedometer will read high, so you are going slower than it says. Overall diameter goes from 30.48″ to 30.43″, a change of −0.1%. 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 265/50R20?
- At an indicated 60 mph you are really doing about 59.9 mph, a −0.1% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 265/55R19 and 265/50R20?
- 265/55R19 turns about 662 times per mile and 265/50R20 turns about 663, a difference of +1. Your speedometer and odometer both count rotations, so this number is what throws them off.