The Biggest Test Of The Biggest Rubber
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.
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.