Interco Tire Corporation builds Super Swamper tires, which are famous for being some of the strongest and best-working tires off-road. "Swampers," as they're affectionately known to the aficionado, have been the tire of choice for many, whether the off-road environment is dry mountain dirt, mud, desert sand, or rocks.
Super Swampers are also famous for the thump they exhibit for a mile or so after they've been sitting for a while. This thump comes from their tough nylon cord. Nylon cord is still the strongest construction, in our opinion, that can be used for tough-environment tire design. Tires built with nylon effectively shrug off sharp rocks and other hazards that leave lesser tires whimpering in fear. The thump goes away after running the tires for a mile and some, so why worry about it? Interco worries about it, as there are evidently potential tire buyers out there who don't like the thump.
When we heard a couple of years ago that Interco was building a new tire to incorporate all the company knew about off-roading, plus be more comfortable on-road, we were skeptical. How could Interco improve on the legendary Swamper's off-road prowess without wimping the tire out for on-road use? Interco answered our question by introducing the IROK tire in both bias and radial designs.
Polyester-cord tires don't thump. Historically, they aren't as strong as nylon tires, but they are more comfortable. Interco decided to try polyester-cord construction for its new IROK. Some of us were so worried that the new polyester tires would be too weak for real off-road use, we talked Interco into building some with nylon cords. While that's another story that should be told by Jimmy Nylund, those tires worked well, but didn't have the performance the new polyester IROKs do.
Our test bias-ply 36x13.50-17LT IROKs were mounted on a Jeep YJ. The load-range D (eight-ply-rated) tires have a maximum load rating of 3,360 pounds per tire at 45 psi, so they'll also work great on our fullsize pickups. They're constructed with four plies of polyester in the tread and four plies of polyester in the sidewall, making for a very beefy tire. The surprising thing was that the tires, while exhibiting really thick sidewalls, still weighed less than all the radial tires of the same size we'd used. This applies to our bias-ply IROKs only, as the radial models of the same size are quite heavy. The IROKs are a true 36 inches in diameter, making them the same diameter as many of the so-called 37-inch tires available today. The 13-1/2-inch section width is about the same as the wider 12-1/2-inch tires available, so don't worry about fitting these new tires to your rig. If the 12-1/2-inchers don't work, these 13-1/2-inchers will.
So, How Do They Work?To sum things up in a word - well. The rounded tread of the IROKs worked so well in the sand that we had trouble spinning them. The Jeep just took off every time we tried to get the photo, until we put it in front-wheel drive and were able to dig in a bit. Friends of ours who use these tires in the snow report superb performance there as well. The strong sidewalls stood up to the sharp rocks we jammed them onto. Beware, though, as any tire can get a hole in it if you try hard enough. For example, shove a knife through any tire's sidewall and see what happens.
The compound of the IROK is fairly soft and very sticky. In fact, when these tires first appeared, people thought Interco was building some special drag-race-compound, non-DOT-approved tire for the rockcrawling competitions. Not so. With the exception of the single run of nylon tires mentioned earlier, the IROKs bought in the store are the IROKs you see everywhere, even in competitions. With this said, they obviously work great in the rocks. Good grip in the rocks means good grip on asphalt, and the IROKs didn't disappoint on-road. Highway performance was good, with the IROKs staying surprisingly quiet at higher speeds. We can't comment on mud performance, as we didn't get into any. The way we use tires isn't conducive to long tread life, so we can't comment on how long they'll last, either. We prefer performance first and tread life last anyway.
The IROKs were mounted on a set of competition-proven Walker Evans 17x8.5-inch alloy bead-lock wheels. Rockcrawling competitors attest to the fact that these wheels are extremely strong. The thick center lug area not only means extra strength, but that Walker can machine the wheels to any backspacing you might need between 3-3/4 and 5 inches. They are quite heavy at 45 pounds, but are very true. They're also built to be a bead lock from inception and are available either cast or polished. We like them both ways. The bead-lock rings have angled seats so that when you tighten the ring down over the bead, the bolt heads sit flat. The valve stems are situated out of harm's way, so you won't be ripping off a stem at the worst possible moment. These are serious bead locks meant for real-world use.
The combination of Interco's IROK bias-ply tires and Walker Evans bead-lock wheels was one of the toughest we've ever tested. The performances of both were topnotch, meaning even those with heavy-duty requirements who want to use their tires and wheels in extreme conditions needn't worry. For great off-road performance, you'll want to check out these tires and wheels.
Interco Tire Corporation
P.O. Box 6
Walker Evans Racing