Product Description
Idler Caster
Specifications: 8.000 inch diameter x 4.000 inch width (8.000" x 4.000" | 8 x 4 wheel | 8 x 4 | 203.20mm x 101.60mm)
Specifications
Wheel Dimensions
| Outside Diameter | 8 |
| Inside Diameter | 2.25 |
| Width Side to Side | 4 |
| Bore Depth | 0.63 |
| Bore Outside Diameter | 2.4404 |
Frequently Asked Questions
Q: What does the -SP suffix mean on the SU S684-XL-SP?
A: The -SP designation typically indicates a specialty or special application variant. The SU S684-XL-SP maintains the same 8x4 dimensions as the standard SU S684-XL, but may have different material formulation, bearing configuration, or performance characteristics. Verify the exact specifications with your parts supplier before substituting a standard SU S684-XL for this variant.
Q: Is the SU S684-XL-SP compatible with the same axle as the SU S684-XL?
A: Yes. Both the SU S684-XL-SP and SU S684-XL share the 2.25 inch inside bore and 30mm bearing ID, making them compatible with the same 8x4 wheel spacing and axle configuration. However, verify your truck manual to confirm that the -SP variant is approved for your model before installation.
Q: Can I mix the SU S684-XL and SU S684-XL-SP on the same truck?
A: Not recommended. Mixing different wheel variants causes uneven wear, steering drift, and premature bearing failure due to inconsistent tread stiffness and rolling resistance. Install matching wheels across all four positions. If you must transition from -XL to -SP, replace all four wheels at the same time.
Q: What is the main difference between SU S684-XL-SP and SU S684-XL-A?
A: The SU S684-XL-SP appears to be a tread-only replacement like the SU S684-XL, not a full assembly like the SU S684-XL-A. The -SP variant is pressed onto an existing hub core. If you need a pre-assembled ready-to-mount wheel with bearings, order the SU S684-XL-A. If you are replacing just the tread and reusing the hub, the SU S684-XL-SP may be the correct choice.
Q: How do I install the SU S684-XL-SP tread?
A: The SU S684-XL-SP is a press-fit tread. Remove the old tread using a bearing puller or hydraulic press by pushing from the back of the hub. Position the new SU S684-XL-SP tread on the hub bore and press it straight on using even pressure. Do not tap or hammer sideways, as this damages the bore. Ensure the tread seats fully and does not wobble before reinstalling the wheel.
Q: What is the expected lifespan of the SU S684-XL-SP compared to other variants?
A: Service life depends on the specific material composition of the -SP variant. If the -SP tread is formulated for higher durometer or specialized surfaces, it may last 20 to 30 percent longer than the standard SU S684-XL. Consult your supplier for the exact tread hardness and material type of the SU S684-XL-SP to estimate durability for your application.