275/55R20 vs 295/35R20
New overall diameter
28.13″
was 31.91″
True speed at an indicated 60
52.9 mph
your speedo reads high
Revolutions per mile
717
was 632, +85
| Measurement | 275/55R20 | 295/35R20 | Change |
|---|---|---|---|
| Overall diameter | 31.91″ | 28.13″ | −3.78″ (−11.8%) |
| Sidewall height | 5.95″ (151.3 mm) | 4.06″ (103.3 mm) | −48.0 mm |
| Tread width | 275 mm | 295 mm | +20 mm |
| Circumference | 100.25″ | 88.37″ | −11.87″ |
| Revs per mile | 632 | 717 | +85 |
| Speedometer error | baseline | −11.8% | reads high |
Diameter overlay
275/55R20 295/35R20
Speedometer check
With 295/35R20 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
22.0 mph actual
35 mph shown
30.9 mph actual
45 mph shown
39.7 mph actual
55 mph shown
48.5 mph actual
65 mph shown
57.3 mph actual
75 mph shown
66.1 mph actual
Common questions
- Will 295/35R20 fit instead of 275/55R20?
- Overall diameter changes 11.8%; 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 28.13″, a change of −11.8%. 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 295/35R20?
- At an indicated 60 mph you are really doing about 52.9 mph, a −11.8% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 275/55R20 and 295/35R20?
- 275/55R20 turns about 632 times per mile and 295/35R20 turns about 717, a difference of +85. Your speedometer and odometer both count rotations, so this number is what throws them off.