Trailer Towing Tech

Inclement weather is here and we all know that safe driving is a must, regardless of the conditions. Add a trailer behind your rig and situations can get pretty nasty, pretty quick. This said, we felt we should do our part to help educate the masses and make our highways and biways that much safer.

A cursory glance at America’s roadways this winter season (all seasons actually) reveals in glaring detail the number of unsafe motorists who unknowingly overload or misload their vehicles and trailers. Aside from the cost of auto repairs resulting from an accident, or the long-term wear and tear on their suspensions, bearings, trailers and more, these folks are also risking life and limb in the interest of getting from Point A to Point B without regard or safety.

If you driven the highways, I’m sure you’ve seen them… trailers so heavy that the rear of a car or truck is dangerously squatted. If this is the case, it’s crucial to understand that you can lose 50% of your steering effectiveness or more! Too much weight over the rear axle can decrease the weight over the front tires so much that steering can be almost completely negated, not to mention the loss in braking performance.

Improperly balanced trailers can be just as bad too. A trailer that’s weighted too much from side to side can cause instability in a turn or even cause uncontrollable weaving while driving down the road. Increase the speed and it’s not a matter of IF you’re going to get in an accident, it’s a matter of WHEN. Moreover, there are several other no-no’s when loading a trailer or driving with a trailer as well and we’ll try to point out a few of them to teach you how to safely drive and check your rig and trailer too.

The first place to start is by choosing a proper trailer hitch. There’s far more to making this decision than price or how it “looks” on your car. Take some time to talk to a qualified and experienced installer, but most importantly tell them what your intentions are with the hitch and what you plan to tow as well. You’ll also need to know the overall weight of the trailer in addition to the items or vehicle(s) that will be placed on or inside the trailer. As a general rule of thumb, I typically then add about 10 to 15% to that number to take into account for luggage, fuel, spare parts and so on that might get added to the trailer at the last minute. Once you’ve got your numbers, you’ll then need to figure out whether or not your vehicle is capable of towing a load this heavy. This is typically determined by three things. 1) Brakes – whether or not the vehicle is equipped with brakes capable of stopping the vehicle and that load in tow in a safe distance and time. 2) Suspension – whether or not the vehicles springs are capable of carrying the tongue weight (The amount of weight at the hitch of the vehicle) of the load or trailer in tow safely. 3) Engine – whether or not the vehicles engine has enough power (torque and horsepower) to safely accelerate with the gross load in tow. All of this information is available in your vehicles owner’s handbook. Here are some things you’ll need to look for:

  1. Vehicle’s maximum towing capacity – This is the total amount of weight the vehicle can safely tow
  2. GTW (Gross Trailer Weight) – This is the total weight of the trailer when it is completely loaded down.
  3. TW (Tongue Weight) – This is the total weight distributed from the trailer to the vehicles hitch in a vertical plane. (NOT the amount of weight or drag that’s transferred during acceleration or deceleration) As a rule of thumb, the TW is 10% to 15% of the GTW

Once you know these figures, talk with your qualified hitch installer or dealer to determine which hitch is best for you. Typically, hitches come in 5 rating classes and which cover everything from passenger cars and SUV’s pulling a modest 2,000 pounds or less, to full-size trucks hauling upwards of 10,000 pounds!

Once you’ve installed the hitch and have loaded the vehicle, here are some questions you’ll have to answer to determine whether or not your load has been loaded correctly.
When it’s fully loaded, do the trailer and hitch drag over bumps? Does your tow rig suffer from sway, road wander and/or fishtailing at speed? Does your vehicle’s rear end sag? Do oncoming drivers at nighttime flash their bright lights at you? If you answered yes to any of these questions, then you need to either adjust your load or get a load-leveling device. Properly adjusting your load is a bit of an art really. The trick is to get as much of the weight properly balanced over the trailers wheels as possible. If the load is placed too far forward on a trailer, the weight will be transferred dangerously on to the vehicles hitch thereby squatting the tow vehicle and losing control of steering. Remember, the vehicle is steered by the front tires and your front brakes do more than 50% of the vehicle stopping power! Too much weight too far back on the trailer and you’re actually trying to lift the rear end of the tow vehicle in the air and you loose braking power and could dangerously fish tail.

If you have any regards for your tow vehicle, the trailer and it’s contents and others on the road, you’ll spend some extra time adjusting the load and test driving the setup down a less-traveled road until you get it right.

Before you head for the open road with a fully-loaded trailer, here are some things you’ll want to check on both your vehicle and your trailer to ensure that you have a safe and pleasurable trip.



Trailer brakes – If your trailer has brakes, it’s most likely come with one of two different styles. Regardless of the style, proper brake maintenance is required more often on trailers than on vehicles because of lack of use. Most trailers are only used a few times a year and typically get rust, debris and other items within the brake systems from lack of use.
Surge Brakes – Surge brakes are less common than electric brakes and work on the principal of a master cylinder hooked directly up to the trailer’s receiver. When the tow vehicle applies the brakes, the trailer tries to shift forward. When this happens the hitch receiver on the trailer is ‘squished’ and brake fluid flows the master cylinder on the trailer to the brakes on the trailer, much like the brake system on your car. Surge brakes work pretty well but need to be maintained much more than electric brakes. Plus, they can tend to lock up when trying to back your trailer up too if you’re not careful and graceful.

     Electric Brakes – Electric trailer brakes are a bit more complicated but generally work a bit better than surge brakes. However, they require that an electric brake activator be installed in the cab of the tow vehicle. There are several variations on this theme of electric brake activators and I won’t get into detail, so ask an authorized and qualified installer about the variations of these.

All trailers should come equipped with an emergency, brake-away braking system. This system is a lanyard or cable that is attached from the trailer to the vehicle. Should the hitch system fail and the trailer breaks away from the vehicle, this lanyard is pulled the brakes on the trailer are activated. I personally believe that trailer brakes should only be serviced by a professional but should cost about $50 per tire.

Vehicle brakes – As important, if not more, as the trailer brakes, your vehicles brakes will be put under more strain than usual so it’s vitally important to make sure that you’re brakes are serviced properly before hitting the open road. Getting your vehicle brake’s serviced typically costs about $40 per tire to have it done by a professional or about $15 per tire to do it yourself.



All passenger vehicles and trucks come equipped with some type of spring (coil or leaf) suspension system and are typically built from the factory with ride comfort in mind, not heavy-duty towing. Additionally, as a vehicle ages with use, springs tend to get softer than when they were brand new. If you’re vehicle is more than 5 years old, but meets all of the other qualifications for safe towing, then you can supplement your suspension in a variety of ways to ensure that your springs are up to the task. A qualified mechanic should install all of the items below if you are unsure how to install them yourself.

  • Overload springs – These springs typically sit on top of the existing leaf (flat type) springs and get bolted into place with large U-bolts. Overload springs only work (typically) when the vehicle’s springs are place under load and begin to flex. These typically give you a comfortable ride when not towing and stiffen the suspension under load. Overload springs can usually be found at your local automotive parts store and installed within a few hours. Cost – about $40
  • Air Bags – Air bags are the crème-de-la-crème of suspension additions. These bags are placed typically above the leaf spring or within the coil spring of the vehicle and are controlled by an electric air pump. Air is forced into the bags and increases the vehicles towing capacity in the same fashion as overload springs. When not in use, you simple deflate the air bags and your vehicle has the same soft, comfortable ride as it did before. Air bags can typically be ordered from a trucking dealer or a suspension manufacturer. Cost – about $150
  • Add-a-Leaf Springs – These springs are used primarily with leaf springs and are placed underneath or within the pack of flat springs. I personally don’t care for these springs as they stiffen the ride of the suspension all of the time as well as lift the rear of the vehicle in the air by as little as an inch or more. Great if you’re into a stiff, bumpy ride and that red-neck, jacked-up rear end look. Add-a-Leaf springs can usually be found at your local automotive parts store and installed within several hours. Cost – about $50
  • Air Shocks – Air shocks are my least favorite suspension modification system and are getting harder and harder to find all of the time (thank goodness). Air shocks are replacement or additional shock absorbers that get placed on the tow vehicle. When you need to stiffen the suspension, you simply pump air into the shocks with an electric on board air pump or a foot pump. The trick with these is to make sure you have equal air pressure in each shock and not to over fill the shocks (both very easy to screw up). Air shocks are best placed in the ol’ nostalgia bin in the back of your garage somewhere, but can usually be purchased as your local automotive parts dealer or hot-rod shop. Cost – about $50



Unless you’re a professional or experienced backyard mechanic, you should have your steering system checked by a professional. Things that you’ll want to look for if you are a seasoned grease monkey are ball joints, bearing play and excessive tie-rod play. There are typically about 5 to 10 greasing points in the vehicle’s steering system. The little nipple looking things that grease gets forced into with a grease gun is called a Zerk fitting. There are now two types of grease fittings on vehicles. The original and still the most popular is the Zerk fitting as described above. It looks like a nipple or an outtey belly button. The other type is a flat, small disc looking thing with a small hole in it. This kind of looks like an inney belly button and requires a special fitting on your grease gun.

The other things to check for in your steering system is excessive steering wheel play. If you can turn your steering wheel (rule of thumb) more than ¼ to ½ inch left or right without the tires moving, you have worn out steering components, which should be replaced. Tow a loaded trailer behind a vehicle like this and it’s amplified considerably and very dangerous.



Each trailer, by law, has to have proper working brake lights, turn signals and safety flashers (hazard lights). Before you hit the open road, be sure to have someone stand behind the trailer while you use your turn signals, both with and without your brakes on. Also, check for proper working order of your emergency hazard flashers. You should also familiarize yourself with the electrical wiring system and the associated plugs that connect your trailer to the tow vehicle. And, you should also bring a small electrical repair kit as well. For about $20 to $25 you can buy the following items at your local automotive parts store. Spare fuses, electrical tape, connectors, spare bulbs, and wire strippers/cutters. If you need to test whether a wire has electricity going through it, you can use one of the spare bulbs.



Prior to your towing trip, you should always check the weather in your area and the areas you’ll be traveling to and through during your outing. If weather seem extreme, you should delay your trip or change your route.



Be sure to check both the vehicle and the trailer tires as well with the following guidelines.
Vehicle tires – Before you venture out, be sure to make a check of the condition of the tires on your rig. Proper air pressure is one of the most important items your can do to keep your tires living longer. You should also check for dry rot or excessive cracking as well. Last, you should check the tread depth on your tires, as a rule of thumb, the tread should be at least as deep as 1/3rd the height of a dime.

 Trailer tires – Trailer tires are different from passenger tires. They are rated differently and constructed differently and you should never, ever put a passenger tire in place of a trailer tire. You should also make all of the checks above for trailer tires as you do for you passenger tires.

Each tire, vehicle or trailer, has specific ratings on them for speed and for load carrying capabilities. The charts below help to identify what type of tires you may all ready have and what they should be replaced with. Check with the owners manual for your trailer or your vehicle as well.





Load Index Pounds Kilograms Load Index Pounds Kilograms
71 761 345 91 1356 615
72 783 355 92 1389 630
73 805 365 93 1433 650
74 827 375 94 1477 670
75 853 387 95 1521 690
76 882 400 96 1565 710
77 908 412 97 1609 730
78 937 425 98 1653 750
79 963 437 99 1709 775
80 992 450 100 1764 800
81 1019 462 101 1819 825
82 1047 475 102 1874 850
83 1074 487 103 1929 875
84 1102 500 104 1984 900
85 1135 515 105 2039 925
86 1168 530 106 2094 950
87 1201 545 107 2149 975
88 1235 560 108 2205 1000
89 1279 580 109 2271 1030
90 1323 600 110 2337 1060


Speed Rating Max M.P.H. Speed Rating Max M.P.H. Speed Rating Max M.P.H.
B 31 K 68 Y 118
C 37 L 75 U 124
D 40 M 81 H 130
E 43 N 87 V 149
F 50 P 94 W 169
G 56 Q 100 Y 188
J 36 R 106 Z 149 +
S 112

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