By Mike McGlothlin
Despite ever-increasing tow ratings for modern vehicles, and namely pickup trucks, owners continue to push the limits. No matter what gargantuan towing figures the manufacturers turn out, it seems there is always something taller, longer, and heavier for the end user to transport. With this being the case, many truck owners explore ways to boost their towing capacity. And while this isn’t technically possible (from an engineering, legality, and regulatory standpoint), there are various ways to improve a truck’s driving experience when operating at its maximum towing capacity. From suspension and axle upgrades to better braking and hitch options, we’ll show you exactly what those improvements are.
Truth Bomb: You Can’t Increase Your Factory Towing Capacity
Technically speaking, you can’t increase your vehicle’s towing capacity. Once built on the assembly line, a truck’s towing capacity, gross combined weight rating (GCWR), gross vehicle weight rating (GVWR) and gross axle weight rating (GAWR) is fixed. However, what you can do is improve the overall experience when you are towing at your truck’s capacity. We know over-loading happens every day, but that doesn’t make it good practice. Your truck was designed and developed to tow a certain amount of weight, and going beyond that throws all of its engineering out the window. Over-loading is harder on axles, the frame, the engine and transmission, the tires and wheels and, perhaps most importantly, the brakes and hitch.
Suspension Aid #1: Air Springs
Air springs are a resourceful way to improve your truck’s performance when loaded at its max GCWR. A relatively simple aftermarket (and in some cases, OEM) towing aid, air springs afford you an enhanced ride quality with a load in tow. But the benefits don’t end there. Air springs help level off your suspension, which restores proper headlight aim and keeps steering and braking performance uncompromised. They also serve to reduce trailer sway and body roll while keeping your suspension from bottoming out. It’s also worth mentioning that air springs can ensure your truck’s factory leaf springs never become over-extended from heavy loads (something that can fatigue them).
Suspension Aid #2: Add-A-Leafs
Leaf spring arrangements are great at spreading the burden of weight over a wide area—which is one of the reasons they’re still in use today. But when leaf springs are saddled with the maximum weight they can handle for prolonged periods of time, fatigue and permanent sagging can result. Stacking an additional leaf spring (or multiple springs) on the existing pack has long-been a means of improving the towing experience. Again, this won’t increase your truck’s towing capacity, but it will enhance the way it performs when it’s attached to a heavy trailer or a hulking load in the bed.
Suspension Aid #3: Coil Springs
Upgraded coil springs can also serve a great supporting role in bettering a truck’s towing performance. They allow for considerably more movement than rigid leaf springs do—hence why their ride quality is so much better than leafs. Available in progressive, linear, or dual rate styles, coil springs can be fine-tuned to provide tremendous ride comfort, and the exact ride quality you’re after. That said, coil springs often fall short when employed in rear suspension systems (which is rare). This is because they can’t carry loads as effectively as leaf springs can or distribute the load across a wide area.
Axle Upgrades: Lower Gearing
One of the most effective ways to improve a truck’s towing experience is to help it get loads up and moving quicker. Swapping the ring and pinion—i.e. changing the axle ratio—by installing lower gearing (a.k.a. higher numeric gearing) accomplishes this. A lower ring and pinion will increase engine rpm in every transmission gear, which means quicker acceleration once you’re already up and moving. Unfortunately, more rpm at any given speed also means more revolutions for the engine to make and more fuel being burned. For this reason, higher numeric gearing almost always coincides with a reduction in miles per gallon.
Extreme Upgrades: Bigger, Stronger Axles
While you can’t officially increase the GCWR or towing capacity(s) of your truck (again, that rating is fixed by the vehicle manufacturer), you can certainly make it more capable of handling a formidable amount of weight. Though highly involved, swapping an axle with a higher gross axle weight rating (GAWR) into place is one way to ensure your axle survives its heavy-duty workloads. For example, by replacing the rear 10.5-inch Sterling in a Ford F-250 Super Duty with a Dana M275 found in late-model single rear wheel F-350’s, you get a higher GAWR and an all-around tougher axle with larger diameter ring gear, bigger and thicker axle tubes, and a higher axle shaft spline count.
Brake Enhancements
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If you’re going to tow heavy, stopping power should be high on your priority list. Building on the axle swap listed above, bigger axles often have larger brakes attached at each end. This means larger diameter rotors, calipers, and pads—along with less heat being generated when in use. And even if an axle swap isn’t in the cards for you and your workhorse, aftermarket brake options can help improve the towing experience. Vented and slotted rotors, lightweight calipers, and direct OEM replacement fitments are all available. Look to Wilwood, Innovative Machining Solutions, or SSBC for proven braking products.
Trailer Brake Controller
This is standard equipment on most newer trucks these days, but an aftermarket trailer brake controller should be mandatory for any older vehicle that’s expected to operate at its maximum towing capacity. Not only is it dangerous to overmatch a tow vehicle’s service brakes by foregoing the use of a trailer’s brakes, but it will also increase their wear and tear exponentially. A properly configured trailer brake controller will allow the truck and trailer to stop much easier and sooner with trailer braking in the mix. But on top of those benefits in safety, trailer brakes will also help preserve the life of the tow vehicle’s braking hardware.
Engine Upgrades
A properly cooled engine is paramount in the towing capacity equation. The addition of a larger radiator can increase cooling capacity, and a thorough cleaning can restore a vehicle’s factory cooling capacity. With age, high-mile radiators often suffer from blocked or partially blocked cooling fins due to accumulation of debris such as dust, grease, oil, dirt, mud, and road grime. Returning your radiator to its former glory is an inexpensive way of optimizing performance when you’re working the engine hard. Power adders such as programmers, air intakes, or aftermarket exhaust systems, can aid the towing effort by helping to get loads up and moving quicker—but take care that their added performance doesn’t build more heat in the engine while doing it.
Get The Right Hitch For The Job
With any ¾-ton or larger pickup truck, the highest towing capacity will come from the use of a bed-mounted hitch such as a fifth wheel or gooseneck ball (whereas an SUV or passenger car is limited to receiver hitch towing). But whether you’re towing via fifth wheel, gooseneck, or receiver hitch, make sure you have the correct class of hitch, one that’s rated to handle the truck’s maximum towing capacity. When sourcing an aftermarket hitch, always err on the side of overkill. For example: if your truck’s maximum fifth wheel tow rating is 18,500 pounds, select the hitch that’s rated for 20,000 pounds.
Frame & Chassis Changes
To reiterate, no changes you make to your tow vehicle will increase its towing capacity. However, that doesn’t mean you can’t work to maximize its performance when operating at its max tow rating. This includes frame and chassis upkeep. While you should never cut or alter the factory frame under a tow vehicle, rust spots and signs of fatigue should be addressed as soon as possible. Keep a watchful eye on structural pieces such as fully boxed sections and crossmembers, and pay special attention to spring hangers and shackles in leaf spring applications, as the bushings frequently deteriorate but often go unnoticed.
