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Off Road Tire Test - Monster Mash

Posted in How To: Wheels Tires on April 1, 2008
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The tower of power (top to bottom) 44-inch super swamper tsl, 46-inch mickey thompson baja claw, 47-inch super swamper ltb, 49-inch super swamper irok, 53-inch michelin xzl, and 54-inch super swamper bogger. (44-inch ground hawg tested but not shown)

Around Here Big Knobby Tires Are Like Candy to a fat kid. We just can't get enough, and the bigger the better. Yes, we know that upgrading to bigger and bigger tires opens up a whole can of worms in the steering, stopping, and suspension departments, not to mention axles and gearing, but never mind that; we love them big rubber doughnuts. Luckily the tire market has answered everyone's wishes with bigger and bigger tires within the past few years, and we recently had the chance to throw sensibility to the wind and go test some of the biggest dot-approved tires known to the 4x4 man.

Coincidentally we found a reader with the property, test vehicle, and the same incoherent adoration for giant rubber as us, and with a few phone calls and shipping tags, we had a motley assortment of tires and wheels arriving for an all-out oversized oval orgy of off-road tire testing. Now you may be wondering what makes this experiment so special compared to all the other tire tests done over the years. The fact is that this one is only bigger because every tire involved is bigger-bigger than 43 inches, that is. Believe it or not the tire industry has grown some massive meats recently, such that there are quite a few tires in the 44-plus-inch tire size coming out to play, and we rounded up as many as we could to see how the different diameters, tread patterns, and wheel sizes worked. In the end, our testing is hardly scientific since we were literally comparing different-sized tires, however, we hope that our results will not only help you decide what treads are right for your type of wheeling, but also help you devise a plan for building your truck around the tires you choose.

Because of all the tires we tested, we also needed to round up some wheels. Since our test truggy was running rockwell axles with its giant 6-on-83/4 bolt pattern, we knew that most off-theshelf wheels wouldn't work. Levi had some old split-rim 20-inch wheels, but we also had tires in the 16.5-inch range to test. Luckily we found that usa 6x6 offers some remanufactured military hummer wheels in a 16.5-inch size with the rockwell bolt pattern. These wheels come with a new pvc plastic internal bead-lock ring that clamps the tire beads when the two-piece wheel is assembled, acting as a double bead lock.

The original eight-lug bolt pattern has been cut out and a plate welded for less offset and a rockwell bolt pattern. Also note the o-ring that is used to seal the wheel halves. Though the 16.5-inch tire and wheel sizes are slowly being phased out, there are still many available, especially in these larger sizes. The affordability of retired military hummer double bead locks in stock or these refurbished usa 6x6 editions make the 16.5 an attractive option.

PhotosView Slideshow

Our test involved getting all the tires mounted, measured, and weighed, and then from smallest to largest running them through a rock pile, up a loose rockclimb, back over some more rocks, up a loose dirtclimb, over some chest-high dirt piles, and then through a mud pit. We found that the loose dirtclimb results were pretty similar between them all, but the rocks and mud really revealed the winners and losers (it's hard to pick a winner when comparing grapefruit to watermelons, but we did).

We also measured the amount of ground clearance of each tire under the differential when run at 10 psi. The entire test was done with the tires at 10 psi to give them all a chance to flex out but still stay on the rims.

Our eyes lit up when levi van kekerix sent us an invite to test tires at his family's landscape yard, r-rockyard in monument, colorado, where they sell everything from fertilizer and top soil to gravel and boulders. Levi and his brother jamie both have big 4x4s and along with their friends they have played with many different make and model tires. The invite stated that levi's battered old homebuilt blazer buggy was outfitted with 21/2-ton rockwell axles designed to turn 44-inch and bigger tires. In addition, they were willing to modify their landscape yard with a rock obstacle, a hillclimb, and a mud pit so we could run each set of tires through an identical loop of tests. Many of levi's friends and family were willing to lend a hand with mounting and swapping tires, pulling a stuck test vehicle from the mud pit, and even cooking a pig for lunch (we would never admit that our stomachs in any way influenced our choice in test location). Thus it was that we ended up flying to the middle of eastern colorado for a few days of muddy mud-tire testing. Special thanks to all involved: levi, jamie, kelly, peg, and dutch van kekerix, brandon lammers, bobby yoder, roger jones, rry off-road, and also ouverson engineering for making some beefy 21/2-ton axleshafts that held up great in our test.

The Contenders

The ground hawg is a old standby that gets a bad rap. However-and we can hardly believe we are typing this-they were amazingly flexible, and excellent in the loose rockclimb. We doubt we'll see rockcrawlers going to the hawgs, but if they are on your radar, don't dismiss them. They could use some center lug trimming, but otherwise we were surprised at their performance. The ground hawgs showed up just as we were wrapping up the test, so we scrambled to get them on the truggy but the bystanders were expecting it to be a waste of time. As we headed to the rock pile, folks were mumbling that the recovery tractor should be close by and ready to go, but the hawgs just wrapped their way around the rocks and pulled the buggy up and over the pile.

SIZE 18.5/44-16.5
LOAD (lbs @ psi) 2,855 @ 30
TREAD 6-ply nylon
SIDEWALL 4-ply nylon
GROUND CLEARANCE (at diff, in) 111/2

We had every intention of testing a set of 53-inch michelin xzl tires, and though they are getting harder to purchase directly from michelin, there are some deals available on military surplus variants or slightly used xzls. We have friends who purchased four tires for under $500 off the internet, and we know usa6x6 sells them both in new or slightly used condition. However, they are a radial tire with one steel sidewall ply and four steel tread plies, and each tire can support 14,540 pounds when filled to 110 psi. These tires are made for massive loads such as hauling missiles. Unfortunately they have such a thick sidewall that we struggled unsuccessfully for an hour attempting to mount one. In the end we would bet these tires would hardly flex, and they are definitely heavy, but if big and cheap are your goals, these are definitely the winner.

SIZE 16.00R20
LOAD (lbs @ psi) 14,540 @ 110
TREAD 4-ply steel
SIDEWALL 1-ply steel
MEASURED DIAMETER (in) 521/2 (used)

The mickey thompson baja claw is one of the few contenders in the test not coming from interco, but it held up great against the swamper family. The claws received some snide remarks from the peanut gallery when first bolted onto the test rig, but quashed when they hit the trail. The traction was impressive in the rocks and makes them a very close second to the iroks. The loose rockclimb wasn't a problem with the claws, but the dirtclimb had these digging into the loose dirt. What it lacks in tread and sidewall flex it makes up with multiple lugs. And some sworn swamper fans were quickly giving the claws respect. In the mud the claws were middle of the road, and though they would not match the irok or ltb for distance in the slop, they could still back out once they were in too deep.

SIZE 19.5/46-15
LOAD (lbs @ psi) 3,{{{200}}} @ 30
TREAD 6-ply nylon
SIDEWALL 4-ply nylon
GROUND CLEARANCE (at diff, in) 131/2

We assume that interco was being asked for a bigger version of their smaller, but tough, ltb bias-ply. So lo and behold, here is the 47-inch "bigger ltb" (it's actually printed on the side). We personally felt they were the best-looking tire in the test. They are big, the lugs are massive yet in perfect scale to the diameter, and they just look tough. Ne small issue with the ltbs, and that is that they are made in china, which might be an issue with some buyers. We found they had good traction in the rocks, especially the sidewall tread, which is helpful when the tires roll under. The traction in big rock is on par with the iroks, while in loose rock the traction is better than iroks. In the mud, they cleaned well, plus the vehicle was able to back out once stopped, where the irok was stopped and couldn't back up.

SIZE 17/47-16.5
LOAD (lbs @ psi) 2,830 @ 30
TREAD 6-ply nylon
SIDEWALL 6-ply nylon
GROUND CLEARANCE (at diff, in) 141/4

The super swamper bogger is the preeminent mud tire from interco and the 54-inch variant holds true to that title. With such a massive diameter the tires roll easily across anything. The mud pit wasn't a problem and the rocks didn't have holes big enough to swallow these. The traction is acceptable and the rolling radius makes short work of almost any obstacle. In fact our biggest complaint with this tire is the lateral traction was a bit lacking mainly due to the tread pattern that is so good in mud. However, our initial impression was that the lugs on the bogger were too small for such a big-diameter tire and that they looked like they should be on a 44-inch bogger. However this didn't seem to be an issue at all with the tire and was entirely an aesthetic complaint.

SIZE 19.5/54-20LT
LOAD (lbs @ psi) 3,640 @ 25
TREAD 4-ply nylon
SIDEWALL 4-ply nylon
MOUNTED WEIGHT (lbs) {{{300}}}
GROUND CLEARANCE (at diff, in) 17

The super swamper irok's description on interco's web site is the result of years of tire development in order to produce an all-around mud, snow, and rock tire and it does that very well. Our 49-inch iroks flexed great and folded around rocks, resulting in awesome traction. Though heavy on the 20-inch rims, they still flung a great deal of mud and seemed the perfect tire when mixed with a set of rockwell axles. These were some of the only tires that actually measured true to their size listing. In the loose rocky hillclimb, they stumbled a little and just dug in rather than climbed, but the big fixed boulder field was their home. In the mud they went just as far as the ltbs, but wouldn't back out when needed, which is odd since we later realized the directional tread was mounted backwards.

SIZE 21/49-20LT
LOAD (lbs @ psi) 3,640 @ 25
TREAD 6-ply nylon
SIDEWALL 4-ply nylon
GROUND CLEARANCE (at diff, in) 15

The original super swamper is still a favorite tire amongst wheelers, but we weren't as impressed by it as we had hoped to be. Though they did well in the rocky hillclimb, they didn't seem to have the traction in the actual rockcrawl section. Also in the loose hillclimb, the tsls matched the iroks in distance, but couldn't match the irok for distance in the mud bog. However, the tsls did seem to clean better than the irok in the mud, so we assume the lack of ground clearance was a factor in its short run. In the end, the tsl will always be a great all-around tire, and a classic tread pattern that-although it may be surpassed by some-is still better than many in the mud-tire market.

SIZE 18.5/44-16.5LT
LOAD (lbs @ psi) 2,855 @ 30
TREAD 6-ply nylon
SIDEWALL 4-ply nylon
GROUND CLEARANCE (at diff, in) 121/2

In the mud pit our tires ranked from longest run to shortest in the following order.

1ST 54-inch Super Swamper Bogger (full run)
2ND 47-inch Super Swamper LTB
  49-inch Super Swamper Irok (tied)
3RD 46-inch Mickey Thompson {{{Baja}}} Claw
4TH 44-inch Super Swamper TSL
5TH 44-inch Ground Hawg
6TH 53-inch Michelin XZL (DNF)

So we collected seven different tires and we wrestled most of them onto rims and then onto our test mule to see how they would do in the rocks, dirt, and mud. We found that big tires can easily roll over big holes and they all offered over 11 inches of ground clearance under our differentials. All of the tires did great, and many amazed us in ways we didn't expect, but if we have to choose one above the pack for best allaround performance, it has to be the ltb. This big monster of a tire is tough looking, has lugs as big as your fist, and did great all around. However, it was followed very closely by the irok, a tire that offers some true height, and we found the irok to be cheaper than its slightly smaller brother. We would take either set for our next monster-truck build; just give us some rockwells, a hot v-8, and parts tough enough to handle big rubber.


Interco Tire
Rayne, LA 70578

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