Trailer Tire Guide (ST Tires)

Your source for trailer tire sizing, load capacity, and safety information.

By TireCalculatorHub Editorial Team·Updated: February 21, 2026

About This Hub

Safe towing relies heavily on proper trailer tires. This hub focuses on ST (Special Trailer) tires, providing tools to analyze sizes with our Universal Converter, check Load Index and Load Range for capacity, calculate Tire Age from DOT codes (crucial for ST tires that often age out), and convert PSI/kPa for correct inflation. Includes key tips for ST tire maintenance, speed ratings, and replacement intervals.

Trailer Tire Hub (ST Tires)

Essential tools and information for ST (Special Trailer) tires.

Key Tools for Trailer Tires

Safe towing starts with the right trailer tires. ST tires are designed for trailer use, with stiffer sidewalls and higher load capacities. This hub links you to critical tools for ST tire selection and maintenance:

Universal Tire Converter

Input your ST tire size (e.g., ST225/75R15) to see its full dimensions.

Load Index & Capacity

Determine the maximum load capacity for your trailer tires based on their load index.

Load Range & Ply Rating

Understand the load range (e.g., C, D, E) and its equivalent ply rating for your ST tires.

Tire Age (DOT Code)

Trailer tires can age out before they wear out. Check the DOT code to find the manufacture date.

Key Tips for Trailer Tires (ST):

Inflation is Critical: Always inflate ST tires to the maximum pressure indicated on the sidewall when cold. This is required to achieve the full load capacity. Underinflation is a primary cause of trailer tire failure.
Speed Rating: ST tires typically have a lower speed rating (often 65 mph or 81 mph) than passenger car tires. Do not exceed this rating, even if your tow vehicle is capable of higher speeds.
Age Matters: Replace ST tires every 3-5 years, regardless of tread depth. Trailer tires often degrade from sun exposure (UV damage) and periods of inactivity long before the tread wears out.
Load Capacity: Ensure the combined load capacity of your trailer tires (add the capacity of each tire) exceeds the trailer's Gross Vehicle Weight Rating (GVWR). Never overload your trailer or its tires.

Use these tools to ensure your trailer tires are safe and appropriate for your needs!

Disclaimer

All tools and information provided on TireCalculatorHub are for informational purposes only. Always consult with a qualified professional before making decisions about your vehicle's tires or modifications.

TireCalculatorHub is not liable for any damages or issues arising from the use of information or tools on this website.