PRODUCT TEST: STI Roctane XD Tires and HD Beadlock Wheels

WHAT IT IS:

The new Roctane XD tire from STI is an eight-ply radial aimed at aggressive UTV racers and recreational riders. The highly wear-resistant rubber compound and tread design were developed for durability in harsh, rocky terrain. RocWall sidewall reinforcement and an extra-thick rim guard protect the tire and wheel from damage. Eight-ply, hard-terrain radials aren’t that unusual, but the Roctane’s range of sizes is. You can get these tires in common sizes like 25s for 12-inch wheels all the way up to huge 32s for 14-inch wheels. Prices start at $130, which is a steal for eight-ply radials. Most start at around $200 per tire.

We wanted to gain some ground clearance and were looking for tougher tires for our Kawasaki Teryx4, so we installed 27-inch Roctane XDs on STI’s new HD Beadlock wheels. The HD Beadlock is available in 12×7 and 14×7 sizes and features an integral beadlock ring that centers the tire and makes mounting easier and more precise than with conventional beadlocks. Rock Crusher-reinforced inner bead lips resist damage to the bead seat. STI HD Beadlocks start at just $104, which is far less than typical beadlocks.

PERFORMANCE:

To test the 27-inch STI Roctanes on our Kawasaki, we ran a cross-country loop of hardpacked dirt trails, rocky uphills and long sand washes on the Teryx4’s original equipment, 26-inch, six-ply Maxxis Bighorn 2.0 tires. Then, we switched to the Roctane/HD Beadlock set and ran the same loop on the same day to keep the test conditions consistent.

We’re happy to report that we had no complaints about the stock Maxxis Bighorns. They’re a popular aftermarket tire choice for many good reasons. They grip very well in a wide variety of terrain, and the tread is open enough for good hookup in sand, too. The Bighorns resist flats well and don’t roll under in hard cornering.

The 27-inch Roctane/HD Beadlock set raised the Teryx4 1-2 inches, which was noticeable, but didn’t hurt cornering stability. The sturdier, eight-ply STI tires were flex free in hard turns, which gave the Teryx a more direct steering feel than the six-ply Bighorns. The ride was unexpectedly smooth for an eight-ply tire; some eight-plies feel rock solid, especially in rocky terrain.

Speaking of rocks, one part of our test loop is a slow, rock-crawling-type section that’s tough on skid plates and tires. We still scraped the Kawasaki’s underside with the 27-inch STIs, but less than with the 26s. That bit of extra ground clearance really helps if you hit the trail on a long-wheelbase UTV with all the seats full. Thankfully, we didn’t need to take advantage of the beadlock’s ability to keep a flatted tire beaded, but knowing we had that security was sweet.

THE VERDICT:

Kawasaki’s Teryx4 comes with very good original equipment tires and wheels, so we’d run them until the tires are done. STI’s eight-ply Roctane radials are a great upgrade, with impressive all-terrain traction and better flat resistance.

We hate to waste precious ride time dealing with tire problems, so we recommend the HD Beadocks too. We have to admit, we didn’t miss the Teryx4 EPS’ luxury SUV-looking wheels.

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