Loaded Radius Comparator
Compare manufacturer-specified static loaded radius between tires. See the deflection under load and the true axle height for each tire.
Compare manufacturer-specified loaded tire radii.
Loaded Radius Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Loaded Radius Comparator Works?
The Loaded Radius Comparator works by placing the static loaded radius (SLR) values from tire maker data sheets side by side with the nominal unloaded radius. The tool uses 3 steps.
Enter each tire
Type the size and the published static loaded radius, for example 245/40 R18 with 309 mm.
Calculate deflection
The comparator subtracts the loaded radius from the nominal unloaded radius of 326.6 mm for 17.6 mm (0.69 in) of deflection.
Compare tires
The comparator lists the axle height gap between 2 tires using loaded values, not nominal values.
Loaded Radius Comparator Formula
The Loaded Radius Comparator formula is Deflection = r_unloaded − r_loaded, and the axle height gap is r_loaded,2 − r_loaded,1.
δ = r_u − r_SLRk = r_SLR ÷ r_uΔh = r_SLR,2 − r_SLR,1- r_u
- Nominal unloaded radius (mm)
- r_SLR
- Published static loaded radius (mm)
- δ
- Tire deflection under load (mm)
Worked example
A 265/70 R17 tire has an unloaded radius of 401.4 mm (15.80 in) and a published loaded radius of 373 mm (14.69 in). The tire deflects 28.4 mm (1.12 in), and the loaded ratio is 92.9%.
Loaded Radius Comparator Conversion Table
The Loaded Radius Comparator conversion table compares unloaded and typical static loaded radius for 6 sizes.
| Size | Unloaded radius | Static loaded radius | Deflection | Loaded ratio |
|---|---|---|---|---|
| 205/55 R16 | 315.9 mm | 296 mm (11.65 in) | 19.9 mm | 93.7% |
| 225/45 R17 | 317.1 mm | 300 mm (11.81 in) | 17.1 mm | 94.6% |
| 245/40 R18 | 326.6 mm | 309 mm (12.17 in) | 17.6 mm | 94.6% |
| 235/55 R19 | 370.6 mm | 348 mm (13.70 in) | 22.6 mm | 93.9% |
| 265/70 R17 | 401.4 mm | 373 mm (14.69 in) | 28.4 mm | 92.9% |
| LT285/75 R16 | 416.9 mm | 387 mm (15.24 in) | 29.9 mm | 92.8% |
Loaded radius values are representative. Each model's value comes from that model's data sheet at its stated load and pressure.
What is Loaded Radius Comparator?
A Loaded Radius Comparator is a tool that compares the static loaded radius of tires, the height from axle center to ground with the tire under rated load. Tire makers publish SLR in data books alongside overall diameter.
Loaded radius runs 5% to 8% shorter than unloaded radius on passenger and light truck tires. Tall, soft sidewalls deflect more than short, stiff sidewalls.
Loaded radius gives the true ground clearance and the true lever arm for torque calculations.
What are the uses of Loaded Radius Comparator?
There are 4 main uses of the Loaded Radius Comparator, including true clearance math and torque accuracy.
True clearance math
Use loaded values for differential and rocker clearance.
Torque accuracy
Use loaded radius as the lever arm in wheel force calculations.
Brand comparisons
Compare 2 models whose nominal sizes match but loaded heights differ.
Suspension setup
Set ride height targets from the real axle height.
Related Clearance & Stance Tools
View All 134 Subtools →Estimate clearance changes from tire radius.
Estimate static vertical gap changes.
Estimate changes toward suspension components.
Estimate tire movement toward the fender.
Estimate changes at the inner wheel edge.
Estimate changes at the outer wheel edge.