Ridge Grapplers Take on the Rubicon
When we first set eyes on our 37x12.50R17 Nitto Ridge Grapplers, it was clear they were not your average all-terrain or mud-terrain tire. This makes sense, as Nitto designed this new Grappler to blur the line between two dominant off-road tire segments. The first thing you notice are the tread voids on the Ridge Grappler, which are far wider than the average all-terrain. The way the voids are oriented though eliminates any noisy “tread slap” that is common with aggressive mud-terrain tires. Tread depth is big too, nearly as big as the Trail Grappler and Mud Grappler.
We managed to get the tires mounted just in time for our annual birthday trip to the Rubicon Trail with some friends. Cake is great, but there's no need to make a wish and blow out the candles with a new set of 37-inch Nittos already waiting for you on your doorstep. The tires took incredibly little weight to balance, even on our old battle-scarred wheels—a testament to Nitto’s excellent construction and quality control practices.
On the 100-mile drive from Reno to the Rubicon, tire noise was the least of our concerns in our 30-year-old leaf-sprung Toyota. Even on a modern Jeep Wrangler or fullsize truck, we doubt tire noise would be an issue. This is particularly impressive given the void size and tread depth of the Ridge Grapplers, and speaks volumes about the research and development that Nitto put into making this new tire.
Once we got to the trail, everyone let us go first in our mini truck. This was partly due to the fact that it was my birthday, but it was also the fact that the rest of the group was just as curious as we were to see how the Ridge Grapplers would perform on the Rubicon.
First up were the granite slabs, where we had to use a little more throttle to get up the polished ledges than we typically need with our Trail Grapplers. After a quick air pressure adjustment to allow the carcasses to flex on our brand new Ridge Grapplers, we were up at the top of the slabs. From there, we had no issues at Walker Hill or the Little Sluice. Our group included fullsize trucks, so we bypassed the Old Sluice on our way to Buck Island Lake. The bypass around Buck Island Lake is slick and off-camber, but the Ridge Grapplers exhibited excellent grip and never caused any sliding or pucker moments, even with Detroit Lockers front and rear.
By this point, no one had any concern about the trail prowess of the Ridge Grapplers as they handled everything thrown at them. Perhaps most impressive was how there was no chunking or tearing of the tread, even when we spun the tires to climb up polished granite obstacles coated in fine dust.
When we got back to pavement, the tires still looked new; and when we aired them up, they were just as quiet and smooth as they had been before we subjected them to miles of punishment.
100 Miles on the Road:
This truck is no trailer queen. We drove over 100 miles from Reno to Loon Lake, the start of the Rubicon Trail. This route includes freeway sections and the infamous Ice House Road, which climbs thousands of feet in elevation as it curves and winds its way to the Rubicon.
Airing Down for the Trail:
For trail use, we aired the Ridge Grapplers down to 12 psi to allow them to conform to the terrain. Our Centerline rims are not equipped with beadlocks to retain the tire, so we didn't push our luck by running lower air pressure than that.
The shoulder grooves on the Ridge Grappler are staggered with alternating widths and lengths to clear out dirt and mud. The lateral grooves zig-zag throughout the tread to provide biting edges that grab any available traction.
Our test truck fits 37-inch Ridge Grapplers thanks to custom Deaver leaf springs on all four corners. Leaf springs are not as sexy as coilovers, but they provide great stability and simplicity for rockcrawling use. The front axle is a Dana 44 and the rear is a Toyota 8-inch, both with 4.88 gears and Detroit Lockers.
The Rubicon Trail plays hosts to events like Jeepers Jamboree, Jeep Jamboree USA and the Rubithon all summer long. We were lucky enough to have the trail to ourselves on a late summer weekend—an unexpected treat. If you want peace and quiet on the Rubicon, you typically need to visit the trail during the week.
All in the Details:
There's a lot going on in the tread of the Ridge Grappler. Notice the knurled bars between the tread blocks. These keep small rocks from puncturing the carcass and also reduce the suction qualities of mud and snow, cleaning out the voids to provide forward traction.
Side-hilling can be an issue with a soft suspension and high center of gravity. The trend in the off-road world is to build vehicles that are lower and wider. The 37-inch tall Ridge Grappler for a 17-inch rim has a lot of sidewall, but the strong, rigid carcass did not exhibit any strange handling even on the most off-camber sections of the trail.
Views for the Few:
The Rubicon may not be the most difficult trail in the country, but it just might be the most beautiful. Pine trees, high alpine lakes and glacially sculpted rocks make for wonderful views that not just anyone can reach in their minivan.
An Unpredictable Nature:
The Rubicon changes each year as Mother Nature pounds the Sierra Nevada with winter snow. This rock on Walker Hill used to be on the other side of the trail, but it let loose a few years ago and made the hill much more interesting.
Rocks, Rocks and More Rocks:
Many of the rocks are rounded and smooth, providing very little traction, particularly when they are coated in dust. However, just as many of them are cracked and jagged, just waiting to rip through a sidewall. Fortunately, this was not an issue for the Ridge Grapplers.
The Little Sluice used to be the crux of the Rubicon Trail, but it was filled with rocks to combat erosion and illegal bypasses on the trail. While this particular obstacle is significantly easier now, there are still plenty of obstacles to make the trail interesting, such as the Soup Bowl, Old Sluice and Big Sluice. All but Big Sluice have bypasses for those who value their sheetmetal.
The 37x12.5R17 Nitto Ridge Grapplers are Load Range D. We were concerned they wouldn't flex well on our relatively lightweight Toyota, given that they can carry 3,525 pounds each at 50 psi, but this was not a concern when we ran the proper air pressure for the trail.
Note the sipes in each tread block of the Ridge Grappler. During winter, these sipes allow a place for water and snow to escape, minimizing the potential of hydroplaning. On the trail, they allow the tread surface to flex and conform to obstacles, maximizing traction.
There are a myriad of narrow obstacles on the Rubicon that can pinch sidewalls and result in flat tires. Our test truck doesn't run full width axles, but we still shoved the Ridge Grapplers into several such situations. The sidewall tread on the Ridge Grapplers did an excellent job of fending off damage, and even acted as part of the tread in these situations, providing forward traction.
This Ain't No All-Terrain:
The tread depth of our Ridge Grapplers was 18/32nds. To put that in perspective, the Nitto Trail Grappler has a tread depth of 21/32nds.
Long Live Traction and Tread:
The Ridge Grapplers struck a great balance between traction on the trail and what we expect to be a long tread life. Some tires rely on a soft compound for traction, but at the expense of tread life. Nitto uses an advanced rubber compound with proprietary tread and carcass design to maximize traction without sacrificing long life.
Just to Be Safe:
We carried a fullsize 37-inch spare Ridge Grappler on the Rubicon, but we never needed it. We haven’t needed to use our fire extinguisher either (knock on wood), but we still like the security of having a fullsize spare tire, particularly for a vehicle we drive to and from the trail rather than trailering.
Sidewall Patterns Choices:
We mounted the 37-inch Nitto Ridge Grapplers on a set of lightweight forged rims from Centerline. Note that the Ridge Grapplers, like many Nitto tires, have two different sidewall patterns. You will want to inform your tire shop about which pattern you prefer and ensure they are all mounted with the same sidewall pattern facing out.
100 Miles and Still Kickin':
After a weekend on the trail we aired the tires back up and made the 100-mile drive home. The Nitto Ridge Grapplers took it all in stride, still running just as quietly and smoothly after a weekend of thrashing on the trail as they did when they were brand new.
We don’t expect everyone who purchases a set of Ridge Grapplers to take their rig over the Rubicon Trail, but it's nice to know you could if you wanted to.