Trailer tires
What does a trailer tire's load range letter actually mean?
A trailer tire's Load Range letter, stamped on the sidewall as B, C, D, E, F or G, tells you two things: how many plies the tire's construction is rated to, and the maximum cold inflation pressure that construction is built for. It does not, by itself, tell you how many pounds the tire carries. That figure comes from a separate load index number on the same sidewall, covered on our trailer tire load index chart.
The mapping below is a published tire industry standard: every ST tire sold in a given load range carries the same ply rating and the same maximum cold psi, regardless of brand. Work out the load range your own axle load requires with the trailer tire load calculator, then use the tables here to shop against a real published rating rather than a brand's marketing name for it.
On this page
What does each load range letter mean?
Load Range E, the common upgrade size for heavier travel trailers, is built to a 10-ply rating and 80 psi maximum cold inflation.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Load range | Ply rating | Maximum cold inflation |
|---|---|---|
| Load Range B | 4 ply | 35 psi |
| Load Range C | 6 ply | 50 psi |
| Load Range D | 8 ply | 65 psi |
| Load Range E | 10 ply | 80 psi |
| Load Range F | 12 ply | 95 psi |
| Load Range G | 14 ply | 110 psi |
An ST tire carries its rated load ONLY at its maximum cold inflation pressure. This is not a car tire: there is no lower door-placard pressure to run to. See the trailer tire inflation chart for how that changes your inflation routine.
Which catalog tires are sold in each load range?
Load range is stamped on the tire regardless of size. These are real catalog examples at each range that this site has verified.
The Carlisle Radial Trail HD ST235/85R16 is the Load Range E option in our catalog, sized for heavier fifth wheels and equipment trailers.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Load range | Catalog tires |
|---|---|
| Load Range D | Goodyear Endurance ST205/75R14 |
| Load Range E | Carlisle Radial Trail HD ST235/85R16 |
Most 15 inch travel trailer tires in this catalog publish a load index and a ply count rather than a load range letter on their own listing, which is why the load index chart is the more reliable way to shop by pound capacity across brands.
How fast can an ST tire go?
Most ST tires are built to an industry speed rating of 65 mph unless the sidewall states otherwise. Some newer ST tires are rated to 75 or 81 mph, and that higher figure has to be printed on the tire itself, not assumed. This is a published limit rather than a rule of thumb, and running above it is a documented cause of tread separation, especially combined with under inflation. See the towing speed limits and tire speed ratings chart for the full picture, including posted road limits.
How long does a trailer tire actually last?
Trailer tires are replaced at 5 to 6 years regardless of remaining tread depth, read from the DOT date code molded into the sidewall.
Rule of thumb Widely taught towing convention rather than a published specification. It is a good starting point and it is not a rating.
| What ages the tire | Why it matters |
|---|---|
| Rubber age, 5 to 6 years | Ultraviolet exposure and heat cycles break down the rubber compound long before the tread wears out on a trailer that sits parked most of the year. This interval is widely taught rather than published by a standards body. |
| The DOT date code | The last four digits of the DOT code are the week and year of manufacture, and reading that code is a published, traceable fact rather than a guess. A tire that shows plenty of tread and a nine-year-old date code is still due for replacement. |
See best trailer tire pressure monitoring systems and tire covers for two of the cheapest ways to extend the years you get before that clock runs out.
Load range at a specific axle load
These generated pages work the exact load range needed for one axle load and axle count: load range for a 7,000 lb 2-axle trailer, load range for a 10,000 lb 3-axle trailer and load range for a 3,500 lb 1-axle trailer.
Frequently asked questions
What is the difference between Load Range D and Load Range E?
Load Range D is an 8-ply-rated construction with a 65 psi maximum cold inflation, and Load Range E steps up to a 10-ply rating and 80 psi. E tires generally carry more load per tire at the same size, but the exact pound figure comes from the load index printed alongside the range, not the letter by itself. See our load range D vs load range E comparison for a size by size breakdown.
Does a higher load range letter always mean a higher pound capacity?
Not automatically. Load range sets the ply rating and maximum psi, and pound capacity is set by the separate load index number at that same maximum pressure. Two tires of different sizes can share a load range letter and carry very different pound ratings, so always check the load index, not just the range letter, before buying.
Can I run a Load Range E tire at a lower pressure than 80 psi?
Running it lower drops the rated load capacity below what the tire is built for, because an ST tire only carries its full rated load at the maximum cold pressure printed on the sidewall. If your trailer does not need the full capacity, choosing a lighter load range sized correctly is safer than under inflating a heavier one.
How do I know what load range my trailer needs?
Work out the load per tire from your trailer's loaded axle weight divided across the tires on the ground, then find the smallest load index and load range combination that covers it with a reserve. The trailer tire load calculator does this arithmetic directly from your own weighed numbers.
Why do ST tires use load range letters instead of just a pound number?
The letter groups tires by construction and maximum pressure across every size a maker sells, which lets a shopper compare an ST205/75R15 to an ST225/75R15 on the same scale before looking at the pound-specific load index. It is a published industry classification rather than a marketing term, and it does not vary between brands.
Is Load Range G overkill for a travel trailer?
For most single and tandem axle travel trailers, yes. Load Range G, at 14-ply and 110 psi, is built for heavy triple axle trailers and large equipment loads. A tandem axle travel trailer under about 10,000 lb typically sits comfortably in Load Range D or E, and oversizing the range does not add a safety margin the way it might seem to.
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Researched, not professional advice. This page is compiled from published standards, manufacturer towing guides and product specifications, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are towing convention rather than published standards, and they are labelled that way wherever they appear. Nothing here overrides your own ratings. Work your payload sum before your tow rating, because payload is the limit that actually binds on most half ton trucks and nearly every SUV. Load a conventional trailer to 10 to 15 percent tongue weight and a fifth wheel to 15 to 25 percent pin weight, and never lighter: a tail heavy trailer is what starts sway. Weigh the rig loaded rather than trusting a brochure dry weight. A weight distribution hitch and a set of air bags both restore ride height and control, and neither one raises a single rating. Trailer brakes are required by state law above a threshold that varies by state, and a breakaway battery that has quietly gone flat is the normal condition of most trailers on the road.