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Does Adding Ballast to Tires Help Trail Performance?

Posted in How To: Wheels Tires on August 1, 2017
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We spent significant time and effort making our Tracker project as light as possible (Part 1, http://www.fourwheeler.com/project-vehicles/1506-we-build-a-lightweight-fuel-efficient-daily-driverrockcrawler-chevy-tracker/). We were rewarded with a vehicle that is nimble and incredibly capable on the trail without requiring a V-8 engine or 1-ton axles. So why would we deliberately add weight? Good question.

Our first exposure to running water in tires was about 15 years ago at a rockcrawling competition. Joel Randall was a competitor at the time, but he is also a farmer from Nebraska. Randall had been putting water in the tires of his tractor for years to increase the traction and keep it from jumping out of the rows of his field. He applied the same principle to his rockcrawling buggy. Soon thereafter nearly all competitors started adding water, lead shot, or some form of ballast to their front tires.

The idea is that the weight added is as low to the ground as can be, lowering the vehicle’s center of gravity and making it more stable. Additionally, the weight is entirely unsprung, which helps keep the tires on the ground and increases traction. The downside? Well, that’s what we were looking to find out. We had only seen water added to tires for slow-speed rockcrawling. Would it ruin our Tracker’s ability to drive down the street? Would it scatter our front axle into little pieces?

In competition crawling, Dana 60 or comparable 1-ton axles with chromoly axleshafts and drive flanges are considered mandatory equipment for running water in the tires. Our Tracker doesn’t have a 1-ton front end; however, it weighs under 3,000 pounds and has a 137hp four-cylinder engine. The Tracker uses a Diamond Axle–fabricated housing that has a high-pinion Toyota 8-inch centersection with 5.29 gears from Nitro Gear & Axle. Admittedly we are pushing our luck with regards to this gearset. The axleshafts are less of a concern since they are chromoly Birfields and shafts from RCV. Similarly, the knuckles are Hellfire Fabrication (now owned by Ruff Stuff) 80 Series knuckles that use trunions instead of ball joints. In short, this is not your standard Toyota front axle.

Even with built axles we don’t recommend adding 80 pounds of ballast to each tire if you use your vehicle for daily driving at freeway speeds. Doing so would increase braking distances and the risk of losing control of your vehicle at speed. When the water gets unsettled in the tires, the result is similar to death wobble, which is no fun at all. These tradeoffs might be worth it, though, if you have a dedicated trail machine and are looking for more capability. Our Tracker has cutting brakes, selectable lockers, and a winch connected to the front axle to compress the suspension. Water in the tires is another tool in that toolbox. Still, we don’t plan on selling off our normal tires and wheels quite yet.

We purchased two additional 37-inch Maxxis Trepadors and 17-inch KMC Enduro beadlock wheels so we would be able to swap back and forth between the tires filled with water and the ones filled with air, for comparison.
Despite appearances, most of the antifreeze we added did make it into the tire. Sometimes it is tough to wrench and shoot photos at the same time! We added about half a cup of antifreeze to each tire to lubricate it and keep the water from freezing in winter.
First we clamped down the beadlock ring and seated the rear bead of the tire, then removed the ring to add water with a hose. This was a relatively fast and easy way to fill the tires and allowed us to see just how much water we added.
If your tires are already mounted on the wheels, an adapter (such as this one from Milton Industries) can be used to mate a hose to the valve stem. This method is considerably slower, though, and air pressure has to be bled off to allow the water to fill the tire.
When originally building our Tracker we made an effort to use lightweight components, such as these brakes from Spidertrax, in order to shed pounds. That effort wasn’t wasted now, even as we add weight back to the vehicle, since those brakes are not only lighter but offer improved stopping power as well.
We would not recommend adding ballast to your tires if you are running stock axleshafts. Our front axle uses RCV 4340 chromoly axleshafts and Birfields that are 30-spline at the differential and the Birfield. Additionally we are running 80 Series Birfields that are considerably larger that Toyota pickup components.
One area of concern we had was replacing the drive flanges on our FJ80 front axle with locking hubs. We previously did this to unlock the front end when we drove the Tracker on the street, but even with the RCV 300M hub gears we were concerned that the Aisin hubs might be the weak link.
Tires that weigh over 200 pounds each are not very easy to mount. We found it easiest to just roll the tire up to the axle and then position the lug studs with the floor jack so we wouldn’t have to lift the tire to mount it.
We added approximately 85 pounds of water to each front tire. This equated to about 10 gallons of water, which was half of the tire. When the tire was on its side we filled the water level to the seam at the middle of the tire.
On the road we found that acceleration and braking were diminished, but not to the extent that we were expecting from the added weight. The biggest issue was that on rough roads that unsettled the water the front end would try to move around and we had to slow down. We would not recommend running at freeway speeds with water in the tires.
On the trail we found that the added weight assisted with stability since all of the weight was down low. Climbing obstacles seemed to be easier once the front end was up; the rear of the Tracker just seemed to follow along.
In the end our weak link was not the axleshafts but rather the tie rod that was responsible for turning the heavy tires. This is an easy fix, and we plan to add a heavier-walled tie rod, but our concern is that our weak link now is a component that’s not so inexpensive or easy to fix on the trail.
To get off the trail, we simply bent the tie rod back to a somewhat straight position with a winch and a strap. Although it’s not visible in the photo, we are running hydraulic-assist steering. The packaging of our steering required the hydraulic ram to be mounted to the pitman arm on one end and the frame on the other end.

Sources

KMC Wheels
Cerritos, CA 90703
877-943-3577
www.kmcwheels.com
RCV Performance
Loves Park, IL
815-877-7473
RCVperformance.com
Maxxis
Suwanee, GA 30024
800-462-9947
http://www.maxxis.com
Spidertrax Off-Road
Longmont, CO 80503
800-286-0898
www.spidertrax.com
Nitro Gear & Axle
Sacramento, CA
916-673-6464
www.nitro-gear.com
Marq Powder Coating
Sparks, NV
775-358-3209
https://www.facebook.com/pages/MARQ-Powder-Coating/197420310322053
Diamond Axle
Red Feather, CO 80545
970-881-2418
http://www.diamondaxle.com/index.htm

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