SUMITOMO ST918
Sumitomo ST918 Commercial Truck Tire User Manual
Model: ST918 (24570R19.5 133Y)
Brand: SUMITOMO
Introduction
This manual provides essential information for the proper installation, operation, and maintenance of your Sumitomo ST918 Commercial Truck Tire. Adhering to these guidelines will help ensure optimal performance, safety, and longevity of the tire. Please read this manual thoroughly before installation and use.
Product Overview
The Sumitomo ST918 is a robust commercial truck tire designed for drive axle applications. It is engineered to provide reliable performance for heavy-duty vehicles.

Figure 1: Sumitomo ST918 Commercial Truck Tire. This image displays the tire's tread pattern and sidewall markings, indicating its design for commercial vehicle applications.
Key Features:
- Designed for Drive Axle applications.
- Non-Directional Tread Type for versatile use.
- Radial Construction for enhanced durability and performance.
- High Load Capacity suitable for commercial vehicles.
Installation and Setup
Proper installation is crucial for tire safety and performance. It is strongly recommended that tire installation be performed by a qualified professional using appropriate equipment.
Safety Precautions:
- Never attempt to mount a tire without proper training and equipment.
- Ensure the tire and rim sizes match exactly.
- Inspect the tire for any damage before mounting.
- Use appropriate safety gear, including eye protection.
Mounting and Balancing:
- Clean the rim and tire bead area thoroughly.
- Lubricate the tire beads and rim flanges with an approved tire lubricant.
- Mount the tire onto the rim, ensuring correct orientation if applicable (though this tire is non-directional).
- Inflate the tire slowly to the recommended pressure, ensuring the beads seat properly. Never exceed the maximum seating pressure specified on the tire sidewall.
- Balance the tire and wheel assembly to prevent vibrations and ensure even wear.
Operation Guidelines
Adhering to proper operating practices is essential for tire performance and safety.
Load Capacity and Speed Rating:
- The Sumitomo ST918 tire has a load capacity of 4540 Pounds. Do not exceed this limit.
- Refer to the tire sidewall for the specific speed rating (e.g., 133Y indicates a maximum speed of 186 mph, but always adhere to vehicle manufacturer recommendations and local speed limits).
- Overloading or exceeding the speed rating can lead to tire failure and serious accidents.
Driving Conditions:
While the ST918 is designed for commercial use, avoid harsh driving conditions such as excessive speeds, sudden braking, or sharp turns, especially when carrying heavy loads. These actions can accelerate tire wear and compromise safety.
Maintenance
Regular maintenance extends tire life and ensures safe operation.
Tire Pressure:
- Check tire pressure regularly (at least monthly) when tires are cold.
- Maintain the inflation pressure recommended by the vehicle manufacturer, not necessarily the maximum pressure listed on the tire sidewall.
- Under-inflation or over-inflation can lead to uneven wear, reduced fuel efficiency, and increased risk of tire failure.
Tire Rotation:
Rotate tires according to your vehicle manufacturer's recommendations or every 5,000 to 8,000 miles to promote even wear across all tires.
Tread Depth and Inspection:
- Regularly inspect tread depth. The ST918 has a tread depth of 21/32nds when new.
- Replace tires when tread depth reaches the minimum legal limit (typically 2/32nds of an inch for commercial tires).
- Inspect tires for cuts, punctures, bulges, or any other signs of damage. Any damaged tire should be inspected by a professional immediately.
Troubleshooting
This section addresses common issues you might encounter with your tires.
Common Issues and Solutions:
- Uneven Tread Wear: Often caused by improper inflation, misalignment, or imbalance. Check tire pressure, and have alignment and balancing inspected by a professional.
- Vibrations: Can indicate an unbalanced tire, bent rim, or suspension issue. Have the tire and vehicle suspension inspected.
- Slow Air Leak: May be due to a small puncture, valve stem issue, or bead leak. Locate the source of the leak and have it repaired by a professional.
- Bulges or Cracks: These are serious indicators of internal damage. Do not drive on a tire with bulges or significant cracks. Replace immediately.
For any persistent or severe issues, consult a certified tire technician or your vehicle service center.
Specifications
| Feature | Specification |
|---|---|
| Brand | SUMITOMO |
| Model | ST918 |
| Size | 24570R19.5 |
| Section Width | 245 Millimeters |
| Load Capacity | 4540 Pounds |
| Tread Depth (New) | 21/32nds |
| Tread Type | Non-Directional |
| Tire Diameter | 21 inches |
| Item Weight | 53 Pounds |
| Construction Type | Radial |
| UPC | 768155373317 |
Warranty and Support
For information regarding the warranty of your Sumitomo ST918 Commercial Truck Tire, please refer to the warranty documentation provided at the time of purchase or visit the official Sumitomo Tire website. Warranty terms and conditions may vary.
For technical support, service inquiries, or further assistance, please contact your authorized Sumitomo Tire dealer or the Sumitomo Tire customer service department.
Always ensure that any service or repair work is performed by qualified professionals to maintain tire integrity and warranty validity.
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