Tractor Tyre Rolling Circumference Calculator
Estimate roll-out, loaded diameter, revs per mile, and wheel rpm from tyre size or measured roll-out circumference.
📌Preset rolling scenarios
⚙Rolling inputs
📊Rolling circumference results
Roll-out and loaded values update instantly as you change the inputs.
Detailed breakdown
📈Reference tables
Common tractor tyre sizes
| Size | Rolling circumference | Loaded diameter | Revs per mile |
|---|---|---|---|
| 320/85R24 | 52.3 in | 50.2 in | 401 |
| 380/85R24 | 55.5 in | 53.3 in | 377 |
| 420/85R34 | 62.1 in | 59.6 in | 339 |
| 480/80R38 | 68.2 in | 65.5 in | 308 |
| 520/85R42 | 76.8 in | 73.7 in | 274 |
| 540/65R28 | 55.6 in | 53.4 in | 377 |
| 600/70R30 | 63.1 in | 60.6 in | 332 |
| 710/70R42 | 81.1 in | 77.9 in | 259 |
Formula guide by roll-out mode
| Mode | Inputs | Math | Best use |
|---|---|---|---|
| Metric size | Width, aspect, rim | D = rim + 2 x sidewall | Modern tyre codes |
| Imperial size | Width, aspect, rim | D = rim + 2 x sidewall | Older tyre codes |
| Direct measure | Measured OD | D = OD | Worn tyres |
| Loaded check | D and deflection | D_loaded = D x (1 - deflection) | Field speed work |
Surface and load correction guide
| Type | Width shift | Deflection | Notes |
|---|---|---|---|
| Radial | 0.0% | 4.0% | Common field tyre |
| Bias-ply | +0.8% | 6.0% | Stiffer sidewall |
| IF/VF | -0.5% | 3.0% | Flexes at low pressure |
| Flotation | +0.5% | 5.0% | Wide footprint shape |
Circumference to revolutions quick chart
| Diameter | Rolling circumference | Revs per mile | Revs per km |
|---|---|---|---|
| 50 in | 157.1 in | 403 | 250 |
| 60 in | 188.5 in | 336 | 209 |
| 70 in | 219.9 in | 288 | 179 |
| 80 in | 251.3 in | 252 | 157 |
Tip 1
Check the loaded roll-out, not just the stamped size. Inflation, ballast, and field load all change the real rolling height, so the live value is what matters for speed and fit.
Tip 2
Compare the new roll-out to the old one before swapping. A small diameter mismatch can change travel speed, axle balance, and dual-tyre match quality more than you expect.
This tractor tyre rolling circumference calculator compares roll-out, loaded diameter, and revs per mile so setup, matching, and field speed checks stay consistent.
The diameters of tractor tyres is measured on the sidewall of the tyre. However, the rolling circumference of the tractor tyre will change when the tractor tyre is under a load in the field. If you dont account for the change in rolling circumference, then the tractor will travel at a different speed then what is indicated on an GPS system.
Additionally, the rates at which the planting and spraying equipment applies the required amount of product to the field will also be incorrect. The rolling circumference of the tractor tyre will determine the actual distance of how far the tractor travel with every revolution of the tractor tyre. The size of the tractor tyre will have specific
Tyre load changes tractor distance, speed, planting and spraying rates
