Trailer Tires: Construction, Pressure, Tread And Cracking

Trailer Tires can have plenty of tread and still be ready for replacement. Construction, cold inflation pressure, loading and rubber condition all matter. We recommend looking at those together instead of judging a tire by how new its tread looks.

Trailer Tires: Radial Versus Bias-Ply Construction

A bias-ply tire uses layers of reinforcing cords that cross diagonally from bead to bead. Those overlapping layers connect the tread and sidewall more closely, creating a relatively stiff casing. A radial tire’s body cords run across the tire from bead to bead, roughly perpendicular to the direction of travel, with belts supporting the tread.

That difference affects how the casing flexes and manages heat. Radials generally handle sustained highway travel better and offer a smoother ride. Bias-ply designs remain useful in certain utility and specialty applications where a stiffer casing suits the work. Neither construction label, by itself, tells you how much weight a tire can carry. Compare the actual tire’s load and speed ratings and the trailer manufacturer’s requirements. Construction Reference.

Do not mix radial and bias-ply tires on the same axle. When changing construction, have a tire professional confirm the complete trailer fitment. Matching wheel diameter alone is not enough.

Which Tire Pressure Number Should You Use?

Start with the trailer’s tire-information placard and owner’s manual for the specified tires. Use the trailer’s information, not the tow vehicle’s door sticker. The tire sidewall lists its load and inflation information; it is not automatically a substitute for the trailer’s recommended pressure. Pressure Guidance.

Trailer-tire instructions vary. Some manufacturers specify maximum rated cold pressure for their trailer tires, while others publish load-and-inflation tables. If the fitted tire size or load range differs from the original equipment, have the trailer manufacturer or a qualified tire professional reconcile the placard, exact tire instructions, actual loaded weights, and wheel and valve ratings. Do not simply choose the lower number or reduce pressure for a softer ride.

Measure Cold, Before Towing

Cold means the tires have not been driven on for at least three hours. It does not mean winter weather. Check before travel, preferably before direct sun heats one side of the trailer. Use an accurate gauge with a range suitable for your tires, and check the spare too.

Pressure normally rises as tires warm up during towing. Do not bleed off that normal increase to bring a hot tire back to its cold target. It will be underinflated when it cools. Recheck and adjust when cold. A tire that repeatedly loses air needs inspection, not an endless cycle of topping it off. If it has been run severely underinflated, have it inspected before reinflating. Hot-Pressure Guidance.

Pressure Cannot Fix Overloading

The maximum load printed on a tire depends on the specified inflation conditions. More air cannot make an overloaded tire, wheel or axle suitable for the load. Weigh the trailer in travel condition with its usual cargo and fluids. Individual wheel-position weights are especially useful because a total axle weight can hide an overloaded tire on one side. Do not assume each tire carries an equal share.

Inspect Tread Across The Whole Tire

Use a tread-depth gauge in the main grooves at the inner shoulder, center and outer shoulder, checking several places around the circumference. Measuring only the easiest outside groove can miss a worn inside edge. Replace tires at 2/32 inch remaining tread, or sooner if damage or manufacturer guidance requires it. Wear bars flush with the surrounding tread indicate replacement is due.

Uneven wear is a reason to investigate. Both shoulders wearing faster can point toward underinflation or excessive loading. Center wear can suggest excessive pressure for the application. One-sided wear can involve alignment or suspension problems; scalloping can involve balance or mechanical issues. These are clues, not a diagnosis. Record the cold pressures, photograph the pattern and have the tire and running gear evaluated before a replacement develops the same wear.

Sidewall Cracking Deserves More Than A Quick Glance

Look at both sidewalls, the area near the rim, and the grooves between tread blocks. Use a flashlight for the inside face without crawling beneath an unsupported trailer. Cracks, cuts, a new outward bulge, exposed cords or a distorted tread area need professional assessment before another trip. Deep splits, visible reinforcement or suspected separation are reasons to stop using the tire.

Do not dismiss cracking as cosmetic because the tire still holds air. A photograph or a fingernail test cannot establish how much structural damage exists. Tire dressing cannot repair degraded rubber. A tire professional may need to remove the tire from the wheel to inspect damage that is not visible outside.

Read The Date Code And Check The Spare

The last four digits of the DOT tire identification number show the production week and year. For example, 2423 means the 24th week of 2023. The complete code may appear on only one side. Follow the tire and trailer manufacturers’ age guidance rather than assuming there is one replacement birthday for every trailer tire. Low mileage and deep tread do not stop aging. NHTSA Tire Safety Guidance.

Make The Walkaround Repeatable

Before a trip, check cold pressure, scan the full visible tread and sidewalls, and inspect the spare. Keep a simple record of pressure, tread measurements and date codes so changes are easier to spot. After a curb strike, road impact or unexplained air loss, arrange an inspection even if the tire initially looks normal.

Tire checks are also a useful reminder to review your stopping system. Our RV Trailer Brake Maintenance: 7 Signs Service Is Due article covers the brake side of trip preparation.

For replacement selection, mounting, internal inspection or questionable cracking, use a qualified tire service provider. The goal is a correctly matched tire that can carry the trailer’s real load at its specified cold pressure, with its condition checked before the next highway run.