275/55R20 vs 295/65R20
New overall diameter
35.10″
was 31.91″
True speed at an indicated 60
66.0 mph
speedometer reads low
Revolutions per mile
575
was 632 · −57
Switching from 275/55R20 to 295/65R20? Everything that changes is below — sidewall, tread width, circumference, revolutions per mile and speedometer error at road speeds.
| Measurement | 275/55R20 | 295/65R20 | Change |
|---|---|---|---|
| Overall diameter | 31.91″ | 35.10″ | +3.19″ (+10.0%) |
| Sidewall height | 5.95″ (151.3 mm) | 7.55″ (191.8 mm) | +40.5 mm |
| Tread width | 275 mm | 295 mm | +20 mm |
| Circumference | 100.25″ | 110.26″ | +10.02″ |
| Revs per mile | 632 | 575 | −57 |
| Speedometer error | baseline | +10.0% | reads low |
Diameter overlay
275/55R20 295/65R20
Speedometer check
With 295/65R20 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
27.5 mph actual
35 mph shown
38.5 mph actual
45 mph shown
49.5 mph actual
55 mph shown
60.5 mph actual
65 mph shown
71.5 mph actual
75 mph shown
82.5 mph actual
Common questions
- Will 295/65R20 fit instead of 275/55R20?
- Not recommended. A 10.0% diameter change exceeds the 5% rule. Expect significant speedometer error, potential clearance and rubbing issues, and stress on ABS, stability control and drivetrain components. Your speedometer will read lower than your true speed. Overall diameter goes from 31.91″ to 35.10″, a change of +10.0%. As a rule of thumb, under 3% is safe, 3–5% needs a clearance check, and over 5% is not recommended.
- How far off will my speedometer read on 295/65R20?
- At an indicated 60 mph you would actually be travelling about 66.0 mph — a +10.0% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 275/55R20 and 295/65R20?
- 275/55R20 turns roughly 632 revolutions per mile; 295/65R20 turns roughly 575. That is a change of −57 revolutions per mile, which is what shifts odometer and speedometer readings.