Product Description
Load Wheel Assembly
Specifications: 4.000 inch diameter x 3.625 inch width (4.000" x 3.625" | 4 x 3.63 wheel | 4 x 3-5/8 | 101.60mm x 92.07mm)
Specifications
Wheel Dimensions
| Material | Cushothane XL |
| Outside Diameter | 4 |
| Inside Diameter | 1.875 |
| Width Side to Side | 3.625 |
| Tread Profile | Angle |
| Bore Depth | 0.623 |
| Hub Width | 3.625 |
| Bore Outside Diameter | 2.0467 |
Frequently Asked Questions
Q: What is the difference between SU 645-XL-A and SU 645-XL?
A: The SU 645-XL-A is a complete load wheel assembly that includes the Cushothane XL wheel, sealed bearing, and mounting hub as an integrated unit. The SU 645-XL is the wheel core alone. The -A designation indicates full assembly ready for press-fit mounting to your truck axle. If you need a complete replacement unit, order SU 645-XL-A. If you need only the wheel component or have a separate hub, order SU 645-XL.
Q: What are the exact dimensions of the SU 645-XL-A hub bore for fitment verification?
A: The SU 645-XL-A has a bore outside diameter of 2.0467 inches, inside diameter of 1.875 inches, bore depth of 0.623 inches, and a 3.625 inch hub width. Width side-to-side (wheel face) is 3.625 inches, with 4.0 inch overall diameter. These dimensions are critical for press-fit compatibility. Measure your truck axle stub diameter and confirm it matches the 1.875 inch inside diameter before ordering. An incorrect bore size will not fit.
Q: Is the SU 645-XL-A press-fit or bolt-on mounting?
A: The SU 645-XL-A uses press-fit mounting, meaning the hub bore slides directly onto the truck axle stub. The assembly must be pressed onto the axle using a hydraulic press or similar tool. Do not attempt to hammer or manually force the assembly onto the axle. Improper installation can damage the bearing seal or crack the hub. If your truck uses bolt-on wheels, the SU 645-XL-A may not be compatible. Verify your original mounting method before ordering.
Q: What tools are needed to install the SU 645-XL-A press-fit assembly?
A: You will need a hydraulic press rated for at least 2-3 tons, a press arbor or sleeve sized to the hub outside diameter, a lift jack or hoist to raise the truck, and a torque wrench to verify hub fastener specifications. Do not use an impact wrench for press-fit installation. Center the assembly carefully on the axle stub before applying pressure. Press slowly and evenly to avoid misalignment or bearing damage. Follow the OEM installation manual for exact pressure and procedure.
Q: Can the SU 645-XL-A bearing be regreased or serviced?
A: No, the SU 645-XL-A uses sealed industrial bearings that are not serviceable. Do not attempt to remove the bearing or add grease. If the bearing develops noise, wobble, or feels loose, the entire assembly must be replaced. Sealed bearing life is typically 5-8 years depending on load and environment. Inspect monthly for unusual sounds. A tight, quiet wheel indicates normal bearing condition.