Truck Tire Load Ratings
Single vs Dual Tire Load Rating
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.
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 type | Application | Why it differs |
|---|---|---|
| Single rating | Steer axle, wide-base single positions | Full load on one tire, heat can dissipate more freely |
| Dual rating | Drive and trailer dual assemblies | Heat 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
Why the mate tire matters
A dual rating assumes the pair is doing shared work under controlled conditions. If one dual is smaller in diameter, significantly lower in pressure, or mismatched in tread depth, the tires no longer share load evenly. The larger or higher-pressure tire may carry more weight, while the lower tire may scrub and build heat.
This is why a single replacement in a dual set is not only a price decision. The remaining mate has to be measured and judged before the replacement tire is approved.
Single tire positions
Steer tires and wide-base singles use single-position load ratings, but that does not make the check simpler. The tire still needs to match axle load, wheel rating, approved rim width, pressure target, and vehicle certification limits. A wide-base single conversion also changes spare tire logistics and roadside service planning.
Record the rating used
When approving a dual-position tire, write down that the dual rating was used. That small note prevents a later review from assuming the larger single rating was the basis for the capacity decision.
What can break the assumption
- One dual is more than the fleet tread-depth tolerance below its mate.
- The inside dual is low but the outside dual is at target pressure.
- Different brands have the same nominal size but different actual diameter.
- A wide-base single is being compared with a dual pair without checking wheel and load data.
Capacity Verification Checklist
- Inspect inside sidewalls.
- Measure both tires in the dual set.
- Use dual rating for dual-mounted tires.
- 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
- Government 49 CFR 393.75 - Tires
- Manufacturer Continental Commercial Vehicle Tire Care Resources
- Site note TruckTireGuide.com editorial notes
Editorial Review
TruckTireGuide.com editorial team
Maintained by an independent editor with fleet tire-program experience in regional Class 8 operations, supported by transportation regulatory research and commercial vehicle technical writing.
Pages are checked against public regulations, manufacturer resources, industry references, and conservative field practice. The site does not approve tires for service or replace qualified inspection.