TruckTireGuide.com Semi Truck Tire Reference

Truck Tire Load Ratings

Single vs Dual Tire Load Rating

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The same tire may show one capacity for single use and another for dual use. That difference matters on drive and trailer axles.

Dual tires share the work only when they are matched, properly inflated, and installed with correct spacing.

This site is for general information only. It does not replace professional tire service, DOT compliance advice, tire manufacturer instructions, vehicle manufacturer recommendations, or fleet policy.

Why dual ratings differ

Dual tires run in close proximity, which limits heat dissipation more than a single tire running alone. Tires in dual service also share load in a way that can become unequal when pressure or diameter does not match exactly. Manufacturer data accounts for these conditions with a lower rated capacity for dual service.

What the difference looks like in practice

As an illustration of the general principle: a common 11R22.5 Load Range G tire may carry approximately 6,175 pounds in single service at maximum inflation, but approximately 5,675 pounds in dual service at the same pressure. These figures vary by tire model — always confirm from the manufacturer's data.

Rating typeApplicationWhy it differs
Single ratingSteer axle, wide-base single positionsFull load on one tire, heat can dissipate more freely
Dual ratingDrive and trailer dual assembliesHeat is trapped between tires; load balance depends on matching

Dual assembly checks

  • Same size and compatible tread depth in each dual set
  • No sidewall contact under load — check dual spacing
  • Correct wheel and spacer setup
  • Valve access for reliable pressure checks on inside tire
  • No debris trapped between tires

Capacity Verification Checklist

  • Inspect inside sidewalls.
  • Measure both tires in the dual set.
  • Treat low pressure on one dual as a load-sharing problem.
  • Replace or correct mismatches before long trips.

FAQ

Why does a dual tire have a lower load rating than the same tire used as a single?

Dual tires run in close proximity, which traps heat more effectively than a single tire dissipates on its own. Heat reduces effective load capacity. Dual tires also share the axle load in a way that can become unequal when pressure or diameter does not match — one tire can end up carrying more than its designed share. Manufacturers set a lower rated capacity for dual service to account for these conditions.

What is a wide-base single tire and how does its load rating work?

A wide-base single tire (also called a super single) replaces a dual assembly with one wider tire per wheel end. Wide-base singles use a single-position load rating that must cover the full load previously carried by two dual tires. They require different wheels and rim widths and are not interchangeable with standard dual setups. Load rating, inflation, and wheel compatibility all need verification before a conversion.

How much tread depth difference is acceptable in a dual assembly?

Many tire manufacturer and fleet programs recommend keeping tread depth differences within 4/32 inch and overall diameter differences within approximately 1/4 inch in a dual set. Larger mismatches cause one tire to drag against the other's rolling circumference, building heat and causing uneven wear on both. Check the specific tire manufacturer's guidance for the allowable matching tolerance in the application.

Source Notes

References are used for context and verification. Exact tire service decisions should use current manufacturer data, applicable regulations, and qualified inspection.