Kevlar Conquers the Cinder Cones

Goodyear’s new MT/R tires work well in an unusual environment.

By Jim Brightly
The Jeep Creep

About 18 miles northeast of Flagstaff, Arizona, on US 89, hard up against the shoulders of the Sunset Crater Volcano—and adjacent to its monument—we found Fun with a capital “F”. Known throughout the Arizona off-road community as the Cinder Cones, you’ll find trails winding between pine trees, hills that make the Glamis dunes look like ant hills, and challenges galore.

You’ll also find plenty of level areas among the trees for camping, whether you’re in a tent, trailer, or motorhome—and plenty of space for entire clubs as well. Watched over by the US National Forest Service, you’ll have to see a ranger for a fire permit; or you could stay next door in the Bonita Campground within the monument (it has running water and flushing toilets).

But let’s get to the reasons for our trip to the Cinder Cones in the first place. Two reasons: It’s a cool place to visit—literally and figuratively—during the middle of an Arizona summer, and we wanted to test the new Goodyear MT/R tires with Kevlar on our 2007 Jeep Rubicon Unlimited (for more information on the modifications to the JK see all six facets of “Polishing a Rubi” here on ORC), so we spent the July Fourth weekend in the high country.

0    This is one of the shorter hill climbs in the Cinder Cone area. Gordon and Cheri Both brought their Cherokee to show us the way. Gordy had let his air down as soon as we hit the cinders.

Over the years that I’ve been testing off-road tires, starting in the ‘70s, I’ve found that almost any tire can exhibit great traction if its pressures are reduced. The real test of a new tread and tire design comes when it’s left at highway pressures and is still expected to perform off road. If you’re familiar with your vehicle’s performance, then you can better evaluate the tires’ performance when they’re full of air.

The one-way tread design of the new MT/R (it must have the correct sidewall facing outward when mounted) appears to be wide open enough to operate well in mud and sand, and the added lugs on the sidewalls promised to add traction in the soft stuff and when the air pressure is reduced. (As I’ve already indicated, the MT/R tires with Kevlar worked very well on the red rocks of Moab, but the soft stuff was still an unknown.)

Cheri’s trying the hill now with Gordy standing by with a camera. The JK climbed these slopes with nary a niggle, even full of air.

On the more level and hard-packed trails, the MT/R tires acted much as they did on pavement: low noise, excellent traction (fore, aft and on curves), with very good stability. When we hit the less-traveled trails—which were steeper and softer—I could feel them digging in slightly, then the sidewall lugs began working and the JK flowed right along through the pines with just a slight increase in RPM and an occasional downshift (albeit I did need low range once we began the climbing, possibly because of the altitude, which was hovering on both sides of 8,000 feet).

Only the extreme trails, both in length and angle, defeated the JK. But now that I know that the Goodyear MT/R tires with Kevlar could conquer the Cinder Cones when full of air, I’ll be returning soon with only 8 pounds in them. Watch out, Cinder Cones!

Many of the hills—or cones—topped out with loops like this one to give successful climbers a 360-degree view.

Looking east-by-southeast, we could almost see the curvature of the Earth the air was so clear and the distances were so great.

Looking back toward Flagstaff, we were able to see several steep trails, which we later explored.

Here’s the “Cadillac Hill” of the Cinder Cones. This is the grand-daddy of all the cones, and only hefty horsepower was the only thing that could get you to the top. We couldn’t even estimate its height, but it dwarfs anything at Glamis.

We did run into some unexpected roadblocks on the trails at the Cinder Cones, purely nature-made, probably from washouts or lightning strikes. Driving in cinders is just like driving in sand. The lower the pressures you can go, the better. Next time I’m going the tackle the cones with only 8 pounds in my Wranglers.