275/55R20 vs 295/65R20
New overall diameter
35.10″
was 31.91″
True speed at an indicated 60
66.0 mph
your speedo reads low
Revolutions per mile
575
was 632, −57
| 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?
- Overall diameter changes 10.0%; section width changes 20 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 31.91″ to 35.10″, a change of +10.0%. 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 295/65R20?
- At an indicated 60 mph you are really doing 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 about 632 times per mile and 295/65R20 turns about 575, a difference of −57. Your speedometer and odometer both count rotations, so this number is what throws them off.