Here�s what to do:
Wash your trailer after each use, especially if it was in saltwater. Do this every time! Rinse every part of the trailer with fresh water, especially the suspension and behind the wheels. Flush out the brakes if your trailer equipped with a flush kit. Saltwater is very corrosive.
The sure things in life are: death, taxes and trailer corrosion. Rinsing will greatly prolong your trailer�s life.
Protect your tailer hardware with Corrosion X spray (available at some boating stores.) Spray the nuts, bolts, leaf-springs, winch gears and all other hardware items.
Use tie down straps. These inexpensive ratchet-type straps help secure your boat to the trailer. Wal-Mart and Home Depot have great prices on tie-downs. Every boat should be secured with several. Tie down the transom and the bow (even if your winch strap is already connected.) Your winch strap is not a tie down strap. I was surprised that my boat towed better with the straps than without. Keep an eye on the news. You regularly see boats that have fallen off their trailers and onto the freeway. It�s amazing.
Grease bearings. Do this every couple of weeks. Remove the hub cover. Locate the "Zirc" grease fitting--it's the "nipple" that fits into the femaie end of a grease gun. Squeeze grease from the gun until bearing are full (but not too full.)
My dealer recommended using heavy duty DISC BRAKE grease on the trailer. Others have suggested using heavy duty marine grease. It�s important that the grease doesn�t degrade in water. Try out Kendall Super Blue grease.
Feel your hubs for excess heat when traveling. They should not feel any hotter than a cup of coffee.
Use Bearing Buddies or other such bearing-saving devices.
Milky grease is a sign that it has been compromised by water. If this happens, repack all bearings.
Repack wheel bearings every six month as part of scheduled maintence. They can be repacked annually if you use a bearing saving device such as Bearing Buddies.
Lubricate your lug nuts/posts so that you will be able to loosen them to change tires. This is especially important if you are fixing a flat by the side of the road. Lug nuts tend to rust easily. Use "Never Seize" grease, Boeshield T-9 or frequent applications of WD-40, penetrating oil or silicone spray. Replace steel lug nuts with stainless steel.
Check your tire pressure. Trailer tires are different from car/truck tires. Check the tire sidewall for correct pressure (usually 50-65 psi.)
Check your tire tread. Use the penny test by inserting a penny into the tread. The tread should touch the top of Abe Lincoln�s head.
Check the lights. Have someone depress the brake pedal and use the turn signal while you stand behind the vehicle and ensure the correct lights illuminate.
Check fastners and all trailer hardware to make sure they're tight.
Use safety chains correctly. Chris-cross the chains below the tongue. Position the hooks to your tow vehicle in such a way that they won't easily "boune off." Even better, use a closed-end fastner.
Do not put too much weight on the trailer. Gear can add a lot of weight - even if your boat can handle all of the gear, look at the weight rating on your trailer and do not exceed the maximum weight.
If you are storing your boat be sure to block and cover your trailer tires. Remember rubber degrades when exposed to sunlight and also rots when exposed to the ground. You may wish to shade your tires. Moving your trailer periodically or jacking your trailer off the ground will help reduce dry rotting of your tires.
As you do with your car, carry emergency equipment for your trailer. Make a trailer emergency kit that contains a spare wheel and tire, lug wrench, wheel chocks, bearing grease, extra hub assembly, extra line (for the winch and tie-down straps), replacement light bulbs, wheel bearings and road flares/markers.