Farming For Traction

Tires are always a hot-button issue among off-road enthusiasts. Being that it’s the only part of your rig that’s actually designed to touch the ground, fitting the right set of rubber under your rig is a crucial investment. Over the years, wheelers have cut, sliced, and heavily-modified light-truck production tires to make them perform better for their specific needs. For mud runners, this often equated to removing complete rows of tread to further the voids between the tire’s tread blocks.

It didn’t take long for a few guys to realize that they were essentially building a tread pattern that was already readily available in the farming world. The use of agricultural (or more commonly referenced as tractor or ag) tires on light trucks and SUVs has been going on for decades. Aside from monster trucks, the performance potential of the large ag tread was capitalized greatly by hole-and-hill mud racers and deep-woods swamp runners. As the rigs progressed, so did the way they used and modified the ag tires. Nowadays, there are specialty motorsports classes dedicated for rigs running ag tires.

If you’ve followed our Top Truck Challenge competition over the past decade, you too have seen the popularity of the mega-sized off-road-only rubber make it onto select rigs. As a matter of fact, we’ve even had past competitors take home the top prize on ag tires. So, what’s the rub? Should we all make the switch to tractor treads or is there more to the farm tire fame?

Tire Market

As diverse as the light-truck tire market is, the agricultural rubber world is just as immense. Tire sizes range from as small as 26 inches to as large as 72 inches, with tremendous width and pattern variations in between. Just like the used truck tire market, there is actually a strong network for pre-owned agricultural tires. The low cost and accessibility of used tractor tires is one of the major reasons for its recent popularity. Given that the demand is lower for a 54-inch ag tire over, say, a 37-inch mud-terrain radial, you can often get a set of used ag tires for a fraction of what you would pay for more street-friendly treads.

For those who live near a farming town, check your local paper for farm auctions. Typically, these types of auctions will have discount machinery and parts. More importantly, they will often have old tractor tires and wheels. Online auction sites (eBay, Craigslist, and so on) are always worth checking out, as are enthusiast forums such as the mud-loving www.trucksgonewild.com/forum. We’ve also compiled a list of new ag tire vendors that you can find elsewhere in this article.

Same, But Different

Ag tires may all look very similar from one to the other, but there is a range of tread compounds, patterns, plies, and construction. We would need another magazine to go into all of the available types. One thing to note is that an irrigation tire is not the same as a tractor tire. Most irrigation tires have thinner sidewalls, which make them lighter, but are said to be not as durable as a tire that’s actually designed to work on a heavy piece of steering equipment, such as a tractor.

You’ll hear and read R1, R2, and rice-and-cane plenty when researching ag tires for light-truck use. The tall-and-narrow, rice-and-cane tires are some of the most accessible, with the biggest following and aftermarket support. Companies such as BKT and West Lake Tire are well-known brands on the enthusiast side and have been used on a few of the past TTC rigs. Similar to the light-truck tire market, both radial and bias versions are offered. The stampings on an ag tire are also much different than what you find on a light-truck tire. For example, 16.9-24 on a typical ag tire would mean the tire is 16.9 inches wide and the rim diameter required is 24 inches.

On the Trail

If there is one area where ag tires typically rule the roost, it’s in the mud. Given that you can get the tires in such extreme sizes, swamp runners gravitate towards them. The large spacing between the voids allows the tires to clean out easily, even at low speeds. Tread compound and low air pressure isn’t as important when wheeling in the mud, so you can pick your pattern of choice and hit the swap. Quite a few of the veteran swamp runners we spoke to implied that it’s best to avoid the overly wide ag tires. The main reason we are told is that the wide patch is extremely hard on the steering axle and seems to rob power more than the tall-and-skinny treads.

We’ve also seen tractor tires in the rocks, but are not sold on the performance that some rally behind. The massive size of the tire can typically be credited with a lot of the tire’s competency in behemoth boulders. Custom grooves and tread modifications can make a major difference over a stock tractor tire. Just like a standard tire, you can deflate tractor tires into the single-digit range to gain more performance and flex from the sidewall. The biggest issue is that many of the ag tires require overly large rim sizes (many in the 24-inch range). This large wheel reduces the sidewall, which lessens terrain absorption off-road. Just like a light-truck tire, if you run in the single-digit air pressure range without beadlocks, you run the risk of losing a bead.

Tractor Chew

Despite the fact that some ag tires are DOT-compliant (speed limited), tractor tires will never take over the light-truck market. One thing that has spurred the popularity of the tractor tire in recent years is the ability to get a set for common 16- and 20-inch wheel sizes. For those who live in the mud, the value and performance of tractor tires is high. On a rig that sees a variety of wheeling environments, we’re just not convinced that the pros outweigh the cons.

Maybe our biggest gripe with the tractor tire isn’t the tires’ performance off-road, but rather the ride quality (or lack thereof). Most tractor-tire-equipped rigs that we’ve spent time in have been pretty rough riding machines—nothing that we would want to spend the day trail riding in. There is also a strong notion that you have to have tremendous horsepower to run tractor tires. We agree with that to a point. If your rig struggles to spin 44-inch Boggers off-road, a heavier set of tractor tires isn’t going to help. But there is more to the equation than weight and tread.

We’ve seen rigs have more issue with shock-load damage (tire spinning, then suddenly grabbing traction) on tractor tires than anything else. The leverage of the paddle-like tread on some of the tires is often too much for the drivetrain components to process. For the most part, tractor tires are best suited on the machines they were built for. Sure, they work great blasting through Florida mud bogs, but the weight, aggressive tread pattern, and fact that you can’t drive them on the road, really pull them out of realm of practicality for most off-road enthusiasts. Have a different opinion? Shoot us an email at ali.mansour@sorc.com. We’d love to see what your tractor-tire rig looks like and hear how it’s used.

Tractor Tire Manufacturers

BKT

888/660-0662, www.bkt-tires.com

Firestone

www.firestoneag.com

Interco Tire

337/334-3814, www.intercotire.com

Michelin

www.michelinag.com

Superior Traction

727/741-2035, www.superiortraction.com

Titan

800/USA-BEAR, www.titan-intl.com/agriculture

West Lake Tires

www.westlaketire.com

Custom Wheel Vendors

As we’ve mentioned, you can find ag tires for common 16- and 20-inch wheels. For larger sizes, you will need a custom wheel and/or a new wheel center to fit your rigs bolt pattern. Companies, such as Plan B (shown here), offer 15- to 38-inch custom wheels and up to 42-inch wheel centers. Each company on our source list has its own spin on wheel building, and many offer everything from basic weld-in inserts to complete wheel sets.

Dirt Road Performance

352/812-0959

Red Barn Customs

810/650-8641, www.redbarncustoms.net

Holden On Motorsports

352/588-4816, www.holdenonllc.com

PlanB-Fab

407/398-3283, www.planbfab.com

Racing In The Dirt

920-358-5198, www.racinginthedirt.com