Your truck may get an oil change every 5,000 miles. Your trailer does not have an engine-hour meter or a convenient maintenance reminder, so it is easy to tow it thousands of miles without servicing anything. That is a bad plan. Trailer wheel ends, brakes, tires, suspension parts, couplers, wiring, and hydraulic components wear differently than truck components. They also sit exposed to moisture, road salt, dust, sunlight, and temperature changes between trips. When a neglected component fails, it often happens at highway speed with a load on the deck.
Here is a no-nonsense service schedule you can actually follow, whether you are running a 7,000 lb equipment or utility trailer twice a week or a lighter cargo trailer a few times a year. The exact interval must always come from the trailer, axle, brake, tire, and component manufacturers, but the schedule below gives you a practical starting point for planning inspections and avoiding preventable roadside failures.
Bearing Repack: The Number One Neglected Item
Wheel-bearing and hub service is one of the most frequently neglected trailer maintenance jobs and one of the most consequential when it is ignored. A bearing that loses lubrication, becomes contaminated, or is adjusted incorrectly can overheat and damage the hub, spindle, brake assembly, wheel, and tire. In severe cases, the result can be a wheel separation or fire.
For many Lippert grease-lubricated axles in the 3,500 lb through 7,000 lb range, the published maintenance schedule calls for the bearings to be cleaned, inspected, and repacked every 12 months or 12,000 miles, whichever comes first. Some heavier Lippert axles have different mileage intervals, including schedules that extend to 36,000 miles, but they still require at least an annual inspection. Oil-lubricated hubs follow a different procedure and normally require the oil level and evidence of leakage to be checked before each trip. Identify the axle and hub type before assuming that one schedule applies to every trailer.
A grease fitting or greaseable spindle does not eliminate the need to remove the hub periodically. Adding grease can replenish lubricant, but it does not let you inspect the rollers, bearing cups, seal surfaces, spindle, brake linings, or inside of the drum. Excessive grease or an incorrect greasing procedure can also force lubricant past the rear seal and contaminate the brakes. Use the grease specified by the axle manufacturer, avoid mixing incompatible grease chemistries, and follow the manufacturer’s procedure rather than pumping grease into the hub until it appears somewhere else.
On a single-axle trailer equipped with a 3,500 lb axle, there are two wheel ends to service. A typical 7,000 lb tandem-axle trailer may use two 3,500 lb axles and therefore has four wheel ends, but the certification label and axle tags should be checked before ordering parts. Bearing numbers, seals, grease caps, brake sizes, and torque procedures can differ even when two trailers have the same advertised GVWR. Service every wheel end that has reached the interval rather than assuming that the cleanest-looking hub represents the condition of the others.
When the hub is removed, clean the old grease from the bearings and inspect the rollers and cups under good lighting. Pitting, spalling, corrosion, scoring, flat spots, chipped rollers, or heat discoloration are reasons to replace the affected bearing cone and cup as a matched set. Install a new grease seal whenever the hub is removed for scheduled bearing service. Bearing adjustment and spindle-nut procedures vary by axle design, so do not tighten the spindle nut as though it were a conventional fastener.
Signs you may be overdue before the calendar says so:
- One hub is dramatically hotter than the others after the same run, or there is a hot-metal smell, smoke, or visible heat damage. Check temperatures only after stopping safely; an infrared thermometer is safer and more useful than testing a hub with your hand.
- A growl, rumble, grinding sound, or unusual vibration is coming from one wheel position while towing.
- There is excessive wheel movement when the trailer is safely raised, supported by properly rated stands under approved frame locations, and the tire is checked at the 12 and 6 o’clock positions.
- Grease or hub oil is leaking around the cap, seal, brake backing plate, wheel, or inside surface of the tire.
Any of those conditions calls for a safe stop and an inspection. Do not keep towing simply because the tire is still turning. A damaged bearing can deteriorate quickly, and continuing to move the trailer may turn a replaceable hub or bearing problem into spindle or axle damage.
Brake Inspection: More Often Than You Think
Electric drum brakes are dependable when they are correctly adjusted, properly burnished, and kept free of grease and wiring problems. They do not have the same dashboard wear warnings found on many modern passenger vehicles, however, and trailer brake performance can deteriorate gradually enough that a driver compensates with a higher brake-controller setting without recognizing the underlying problem.
Check brake operation before every trip. Confirm that the tow vehicle recognizes the trailer, that the controller applies the trailer brakes, and that the brakes engage evenly during a low-speed functional test in a safe location. Also inspect the seven-way connector, breakaway cable, visible wiring, and the area behind each wheel for grease or oil contamination.
Manual-adjust electric drum brakes commonly require an initial adjustment after the new brake components have seated, often at approximately 200 miles, followed by adjustment around every three months or 3,000 miles. Self-adjusting brake assemblies are designed to maintain shoe clearance during normal operation, so they do not use the same routine manual-adjustment procedure, but they still require regular inspection. Identify which brake assembly is installed before turning the star wheel or assuming the brakes will adjust themselves.
For normal use, a full brake inspection should be completed at least annually and at the applicable axle-manufacturer mileage interval. Trailers used frequently, operated near their rated capacity, driven in stop-and-go service, exposed to water or corrosive material, or regularly taken through steep terrain may need brake inspections in 3,000- to 6,000-mile increments. A full inspection includes the shoes or pads, magnets where applicable, drums or rotors, adjusters, springs and hardware, seals, wiring, controller output, and the mechanical condition of the hub.
Brake magnets do not have one reliable replacement mileage that applies to every trailer. Their service life depends on adjustment, drum condition, brake usage, electrical current, contamination, and heat. Inspect the magnet face for even contact and normal wear. Replace a magnet or brake assembly when the wear is uneven, the coil becomes exposed, the face is abnormally grooved, the lead wires are damaged, or electrical testing falls outside the component manufacturer’s specification.
If you are towing a Diamond C LPX low-profile equipment trailer or an HDT hydraulically dampened tilt trailer near its rated GVWR, especially on hilly routes, the braking system is doing substantial work. A date-only annual inspection may not be enough for that operating pattern. Use mileage, duty cycle, brake temperature, terrain, and inspection findings to shorten the interval. Some heavier trailers may use electric-over-hydraulic drum or disc brakes rather than conventional electric drums, and those systems have additional fluid, actuator, hose, caliper, bleeding, and compatibility requirements.
Brake condition is also a legal issue. Indiana law requires a trailer or semitrailer with a gross weight of at least 3,000 lb to have adequate brakes that can control, stop, and hold the vehicle. The driver must be able to apply those brakes from the cab, and the trailer brakes must apply automatically if the trailer accidentally separates from the tow vehicle. Loose adjustment, worn linings, contaminated brakes, failed wiring, or a discharged breakaway battery can reduce both service-brake and emergency-breakaway performance.
Check the breakaway switch, cable, battery, charger, and wiring before each use according to the system manufacturer’s instructions. Battery chemistry and expected service life vary, so replacement should be based on the manufacturer’s interval and an actual charge or load test rather than age alone. Replace any battery that is swollen, leaking, physically damaged, unable to hold a charge, or unable to power the brakes as designed. Do not use the breakaway system as a parking brake, and do not leave the pin pulled longer than the prescribed test because doing so can discharge the battery and overheat electric brake magnets.
The Annual Inspection: What It Actually Covers
Once a year, perform a complete inspection rather than treating “annual service” as another name for adding grease. Chock the wheels, unload the trailer when practical, use a jack with sufficient capacity, support the trailer under manufacturer-approved frame locations, and never rely on a hydraulic jack by itself. Do not lift or support the trailer by the axle tube unless the manufacturer specifically authorizes that method. For dump and tilt trailers, never work beneath a raised body or deck without the specified mechanical body prop or support securely engaged.
Here is the full list:
| System | What to Check | Replace When |
|---|---|---|
| Wheel bearings | Clean and inspect rollers, cages, cups, seal surfaces, spindle condition, adjustment, lubrication, corrosion, pitting, spalling, scoring, and heat discoloration | Replace the affected cone and cup as a matched set if there is pitting, spalling, corrosion, a damaged cage, chipped or flattened rollers, scoring, or heat damage; install new seals during scheduled hub service |
| Brake shoes | Measure lining thickness and inspect for contamination, abnormal wear, scoring, pitting, gouging, loose lining, or heat damage | For applicable Lippert electric drum brakes, replace at 1/16 inch of lining or less, or sooner if the lining is loose, deeply damaged, or contaminated by grease or oil; follow the exact axle manual |
| Brake magnets | Inspect face contact, wear pattern, wiring, coil exposure, mounting, and current draw or electrical resistance as specified | Replace when the face is worn unevenly or abnormally grooved, the coil is exposed, the leads are damaged, or electrical readings are outside specification |
| Tires | Check cold inflation pressure, tread depth, load range, size, speed rating, uneven wear, cuts, punctures, bulges, sidewall cracking, valve stems, and the DOT tire identification date | Replace at the wear bars or approximately 2/32 inch of remaining tread, after a nonrepairable puncture, or when there are bulges, exposed cords, significant cracking, repeated pressure loss, impact damage, or the tire manufacturer’s age limit has been reached |
| Lights | Verify running, stop, turn, clearance, license-plate, and marker lights; inspect grounds, connectors, junction boxes, harness routing, and corrosion | Repair any failure before towing; replace damaged lenses, corroded terminals, failing sealed lights, pinched wiring, or connectors that no longer retain a reliable connection |
| Coupler and hitch ball | Confirm the correct ball or hitch size, ratings, latch engagement, lubrication, mounting hardware, gooseneck or pintle components, safety chains, hooks, and breakaway-cable routing | Replace components that are cracked, bent, distorted, excessively worn, difficult to lock, missing retainers, or unable to remain securely coupled; never weld or modify a rated coupler without manufacturer approval |
| Frame and welds | Inspect the tongue, gooseneck, main frame, crossmembers, spring hangers, ramp mounts, jack mounts, tie-downs, and high-stress weld areas for cracks, distortion, corrosion, or movement | Remove the trailer from service if a structural crack, torn hanger, bent frame member, or significant deformation is found; obtain guidance from the manufacturer or a qualified trailer-repair professional |
| Floor (wood decks) | Look for soft areas, rot, splitting, chemical damage, loose or missing fasteners, raised boards, and deterioration around the edges and between crossmembers | Replace affected boards or sections when they cannot reliably support and retain the intended load; tighten or replace deck hardware using the correct fasteners |
| Breakaway battery | Test switch operation, battery condition, charging circuit, cable attachment, wiring, terminals, enclosure, and the battery’s ability to supply the required brake current | Replace when the battery fails the specified test, will not hold a charge, is swollen or leaking, has damaged terminals, or reaches the battery manufacturer’s stated replacement interval |
| Suspension | Inspect springs, equalizers, shackles, bushings, wet bolts, U-bolts, hangers, torque hardware, air-suspension components where equipped, and evidence of axle movement or uneven tire wear | Replace bent or cracked springs, worn-through bushings, elongated holes, damaged equalizers, loose or stretched U-bolts, cracked hangers, or fasteners that cannot be torqued to specification |
| Hydraulic systems | On dump and tilt trailers, inspect hoses, cylinders, fittings, pivot pins, pump, reservoir, wiring, battery, remote controls, fluid level, leaks, and mechanical body props | Replace leaking or abraded hoses, damaged fittings, worn pins, unreliable electrical components, or any part that cannot hold or control the body safely; use only the specified hydraulic fluid |
This basic inspection applies to utility, cargo, dump, tilt, and equipment trailers, but the parts and intervals are not identical across all brands or axle capacities. Current Diamond C premium lines, including FMAX, HDT, LPT, LPX, WDT, and DEC trailers, use Lippert axles as standard. Other trailer brands, older models, and individual configurations may use Lippert, Dexter, or another axle supplier. The axle identification tag, trailer VIN plate, build sheet, and component manuals are the correct sources for bearing sizes, brake type, lubricant, service interval, and torque values.
Mileage-Based vs. Time-Based: Which One Wins?
Both matter because trailers deteriorate even when they sit. Tires age from heat, sunlight, oxygen, ozone, and storage conditions rather than from tread wear alone. Moisture can enter hubs through damaged seals or temperature cycling. Bare brake surfaces can corrode during storage. Batteries self-discharge, electrical connections oxidize, hydraulic-cylinder rods can corrode, and wooden decks can hold moisture around fasteners and crossmembers.
A trailer that travels only 500 miles a year still needs a thorough annual inspection. Low mileage does not verify that the grease is uncontaminated, the breakaway battery is healthy, the tires have not aged, or rodents and corrosion have not damaged the wiring. Trailers stored outdoors, parked on damp ground, used seasonally, or exposed to road salt may need additional storage inspections even when their annual mileage is very low.
Mileage matters as well. A trailer running 15,000 miles a year on grease-lubricated 3,500 lb through 7,000 lb Lippert axles reaches a 12,000-mile bearing-service interval before the 12-month date. A heavier axle with a different published mileage interval may not, but it still reaches the annual requirement. The controlling interval is whichever applicable limit arrives first, adjusted further for unusually severe service.
Use the tow vehicle’s trip or maintenance records to estimate trailer mileage if the trailer has no hub odometer. Record the date, mileage, parts used, bearing and seal numbers, brake measurements, tire DOT dates, lug torque, and any abnormal findings after every service. A basic maintenance log is much more reliable than trying to remember whether the bearings were packed “last spring or the spring before.”
Here is a quick reference schedule:
- Every use: Perform a walk-around inspection. Check cold tire pressure, tire condition, wheel and hub appearance, oil level on oil-lubricated hubs, lights, coupler engagement, hitch-pin retention, safety chains, breakaway cable, breakaway battery and switch, brake-controller connection, doors, gates, ramps, jacks, cargo securement, and visible hydraulic leaks.
- During the first trips and after wheel removal: Follow the axle and wheel manufacturer’s lug-nut seating schedule. Lippert guidance commonly calls for rechecking torque after approximately 10, 25, and 50 miles following installation or wheel removal. New manual-adjust electric brakes may also require adjustment after approximately 200 miles, and new brake shoes and magnets must be burnished according to the brake manufacturer’s procedure.
- Every 3,000 miles or 3 months: Check manual brake adjustment, tire wear, suspension condition, wheel fasteners, brake wiring, and signs of hub leakage. Verify torque using the value specified for the exact stud, nut, wheel material, wheel size, and axle configuration rather than using a universal number.
- Every 6,000 miles or 6 months for frequent or severe-duty users: Inspect brake magnets and linings, controller operation, suspension parts, spring and hanger condition, hydraulic components, wheel-end temperature patterns, and tire wear. Pull the drums sooner when braking becomes uneven, controller gain continually needs to be increased, grease appears near the backing plate, or the trailer regularly works near its rated capacity.
- Every 12 months or the axle manufacturer’s mileage limit: Complete the full annual inspection. For many Lippert 3,500 lb through 7,000 lb grease-lubricated axles, clean, inspect, and repack the bearings by 12,000 miles. Heavier axles may have a different mileage schedule, but annual inspection still applies. Replace tires and breakaway batteries according to condition, testing, service history, and the component manufacturer’s age limits rather than waiting for a roadside failure.
A Note on Trailer Tires Specifically
Special Trailer, or ST, tires are engineered for trailer service and are selected according to size, construction, load range, inflation pressure, speed rating, wheel rating, and the trailer manufacturer’s requirements. Tire size by itself does not tell you the load capacity. For example, an ST205/75R15 may be offered as a Load Range C tire rated around 1,820 lb at 50 psi or as a Load Range D tire rated around 2,150 lb at 65 psi. Those ratings cannot be interchanged, and the correct pressure must come from the trailer certification label and the tire manufacturer’s load and inflation information.
A 7×16 enclosed trailer with a 7,000 lb GVWR may use ST205/75R15 tires, but that is not universal. Do not order replacements from trailer dimensions or GVWR alone. Match the original approved size and construction, provide enough capacity for the actual axle load, confirm that the wheel supports the required pressure and load, and make sure all tires on an axle are compatible. Adding the four sidewall capacities together also does not redefine the trailer’s GVWR. The trailer remains limited by its certification rating and by the lowest-rated relevant component, including the frame, axles, suspension, hubs, wheels, tires, coupler, and safety equipment.
Underinflation is a major source of tire heat and structural damage. Check pressure when the tires are cold, including the spare, and use an accurate gauge. Do not bleed pressure from a warm tire merely because its pressure increased during travel; that rise is expected. Investigate repeated pressure loss, mismatched wear, or one tire consistently running hotter than the others. Uneven wear can indicate incorrect inflation, overloading, bent or misaligned axles, worn suspension components, damaged wheels, brake drag, or a tire that has suffered internal damage.
Trailer tires also age while parked. There is no single federal rule requiring every trailer tire to be replaced at exactly five, six, or seven years. Tire and vehicle manufacturers commonly publish age-based inspection and replacement recommendations that may fall within a range of approximately six to ten years, depending on the product and service conditions. Follow the tire manufacturer’s limit, inspect the tires regularly regardless of tread depth, and shorten the service life when there is cracking, bulging, repeated pressure loss, impact damage, unknown history, prolonged UV exposure, or severe heat and load service.
A tire failure can destabilize either a single-axle or tandem-axle trailer. Tandem axles may provide temporary support after one tire loses pressure, but they do not make a blowout harmless, and the remaining tire can quickly become overloaded. If a tire fails, keep a firm grip on the steering wheel, avoid abrupt steering or hard braking, reduce speed smoothly, activate the hazard lights when appropriate, and move to a safe stopping location. Do not continue towing on the remaining tire unless necessary to reach immediate safety.
Check the DOT tire identification number on every tire purchased with a used trailer. The final four digits identify the week and year of manufacture; for example, 1524 means the tire was manufactured during the fifteenth week of 2024. The complete identification number may appear on only one sidewall. An older tire with good-looking tread is not automatically safe because internal aging, previous underinflation, repairs, overloading, and storage history may not be visible. When the history is unknown, have the tire inspected and compare its age with the manufacturer’s published replacement guidance before placing the trailer into regular service.
When to Call a Shop vs. DIY
Bearing service, manual brake adjustment, light replacement, basic electrical testing, and routine inspections can be reasonable DIY work for someone who has the correct service information, tools, lifting equipment, and mechanical experience. Useful equipment includes wheel chocks, a jack and stands rated for the loaded trailer, a torque wrench covering the required range, a seal puller, bearing packer, suitable cleaning supplies, an infrared thermometer, a multimeter, new seals and retainers, and the exact lubricant specified for the axle.
Many Lippert grease-lubricated wheel ends specify an NLGI No. 2 lithium-complex extreme-pressure grease with corrosion and oxidation protection, but you should confirm the specification for the exact axle. Do not mix incompatible grease types. If changing grease chemistry, remove the old lubricant completely before repacking. Oil-bath hubs require the specified gear oil and are not serviced by packing the cavity with bearing grease. Keep all lubricant away from brake friction surfaces.
Use safe brake-cleaning practices. Do not blow brake dust into the air with compressed air or sweep it dry. Use an approved brake-cleaning method and appropriate personal protective equipment, especially when servicing an older trailer whose lining composition is unknown. Replace grease-contaminated friction material rather than trying to wash it and put it back into service.
Replacing a complete electric brake assembly may be within the ability of an experienced owner, but drum or rotor machining should be performed by a qualified brake or machine shop and only when the component remains within its stamped or published service limit. Many integrated hub-and-drum assemblies are more appropriately replaced when they are worn beyond specification. Hydraulic drum and disc systems require additional knowledge of brake fluid, bleeding, actuator operation, flexible hoses, calipers, and compatibility between the trailer actuator and tow vehicle.
Bring the trailer to a qualified shop when you find corrosion or water contamination inside a hub, a damaged spindle or bearing seat, a drum or rotor outside its service limit, repeated seal failure, an axle that appears bent or misaligned, abnormal tire wear that returns after tire replacement, unreliable hydraulic operation, cracked spring hangers, frame or tongue cracks, or a coupler that is distorted or no longer locks securely. Structural repairs, axle alignment, brake machining, welding on a rated frame or coupler, and diagnosis of recurring wheel-end heat are not “tighten it and see” situations.
Spencer Trailers stocks trailer parts and can help identify the correct service path in the Spencer area. Bringing the trailer VIN, axle tag information, brake size, wheel and tire information, and photographs of the affected parts will make identification faster. If you are considering a used trailer and want a pre-purchase inspection, or you have found a problem and are not sure whether it is safe to tow, reach out here and we can help you figure out the next steps.
What About New Trailers?
New trailers from manufacturers such as Diamond C, H&H, and Wells Cargo are assembled and inspected before delivery, but new does not mean maintenance-free. The important early-service items are normally wheel-fastener torque, brake burnishing, manual brake adjustment where applicable, tire pressure, coupler operation, and inspection for anything that shifted or loosened during the first loaded trips. There is not one universal requirement to repack every new trailer’s bearings at 1,000 or 2,000 miles. Use the axle manufacturer’s published bearing interval unless an inspection, contamination, overheating, storage history, or another service condition calls for earlier work.
After a new wheel has been installed, or after a wheel has been removed and reinstalled, check lug-nut torque at the intervals specified in the axle and wheel documentation. Lippert guidance commonly uses checks at approximately 10, 25, and 50 miles. Torque values vary significantly. Depending on the stud diameter, nut design, steel or aluminum wheel, wheel size, and single- or dual-wheel configuration, the correct value may range from around 90 ft-lbs to well over 300 ft-lbs. Never apply a memorized 90- or 100-ft-lb figure to every trailer.
New electric drum brakes also require a controlled burnishing process so the shoes and magnets develop proper contact with the drum. Follow the brake manufacturer’s instructions and perform the procedure only in a safe location. Manual-adjust brakes should then be checked after the initial seating period, commonly around 200 miles. Self-adjusting brakes still need their operation verified, and any weak, delayed, or uneven braking should be investigated rather than masked by continually increasing controller gain.
Current Diamond C premium trailer lines use Lippert axles as standard. Other brands and configurations may use Lippert, Dexter, or another axle manufacturer, so confirm the component identity instead of relying on a general brand assumption. The trailer certification label gives the GVWR and GAWR, while the axle tag, build sheet, component labels, and owner documentation identify the axle and brake system needed for accurate service information.
If you purchased a new trailer from us and are not sure where to start, browse the inventory pages to review current configurations and model information. The listing, trailer VIN plate, build documentation, and axle tags can then be used to locate the correct manuals and replacement parts. Our team can also help identify the axle rating, brake size, wheel hardware, seals, and service schedule for the specific trailer.
Consistent trailer maintenance is straightforward when it is recorded and performed on schedule. The cost varies by axle capacity, hub type, seal condition, brake system, and whether worn components are discovered, so a single parts-price estimate does not fit every trailer. What is consistent is that scheduled inspection and lubrication cost far less than replacing a damaged spindle, axle, tire, wheel, brake assembly, hydraulic component, or cargo after a preventable roadside failure. Put the annual date on your calendar, track towing mileage, and add inspections whenever the trailer has been overloaded, submerged, stored for a long period, exposed to road salt, or operated under severe conditions.
Got questions about what your specific trailer needs? Give us a call at (812) 829-0226 or stop by 291 West State Hwy 46 in Spencer. Bring the VIN or a clear photograph of the axle tag when possible. We can help you identify the installed components and build a maintenance schedule that fits how you actually use your trailer.
