275/55R20 vs 265/35R20
New overall diameter
27.30″
was 31.91″
True speed at an indicated 60
51.3 mph
your speedo reads high
Revolutions per mile
739
was 632, +107
| Measurement | 275/55R20 | 265/35R20 | Change |
|---|---|---|---|
| Overall diameter | 31.91″ | 27.30″ | −4.61″ (−14.4%) |
| Sidewall height | 5.95″ (151.3 mm) | 3.65″ (92.8 mm) | −58.5 mm |
| Tread width | 275 mm | 265 mm | −10 mm |
| Circumference | 100.25″ | 85.78″ | −14.47″ |
| Revs per mile | 632 | 739 | +107 |
| Speedometer error | baseline | −14.4% | reads high |
Diameter overlay
275/55R20 265/35R20
Speedometer check
With 265/35R20 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
21.4 mph actual
35 mph shown
29.9 mph actual
45 mph shown
38.5 mph actual
55 mph shown
47.1 mph actual
65 mph shown
55.6 mph actual
75 mph shown
64.2 mph actual
Common questions
- Will 265/35R20 fit instead of 275/55R20?
- Overall diameter changes 14.4%; 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 31.91″ to 27.30″, a change of −14.4%. 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 265/35R20?
- At an indicated 60 mph you are really doing about 51.3 mph, a −14.4% 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 265/35R20?
- 275/55R20 turns about 632 times per mile and 265/35R20 turns about 739, a difference of +107. Your speedometer and odometer both count rotations, so this number is what throws them off.