A Test of the Yokohama Geolandar X-MT on the KOH Course

When you pair up with a Jeep legend like Tony Pellegrino and the GenRight Family, there is only one place you can go to debut a tire: Johnson Valley OHV Park and the Hammers. He knows the trails and took a group of us out along the 2018 KOH course, so we could not only experience the terrain, but also see how well these tires worked. If there is one place to do that off-road, it’s those trails.

Yokohama Tire invited me out to try this new Geolandar X-MT, which is why this article is going up for everyone at the same time, no matter if they are a free user, a Monthly, an Annual, or a Biannual Subscriber. They set me and the group up in a set of motorhomes, so we could stay overnight at the Ultra4 Compound in Landers, CA, along with food and live music.

Tony Pellegrino and GenRight

I also know Tony well from working out at the King of the Hammers and being friends with a few of his race team sponsors, past and present. I’ve also worked with him and GenRight on articles in my freelance career and have another article as well as several more coming with he, Jordan, Jami, and the GenRight Team soon. However, if you want to see stuff like that two weeks sooner or get Premium content for being an Annual or Biannual member, subscribe here!

The Geolandar X-MT

That out of the way, let’s talk about that tire. The Geolandar X-MT is designed to be an “extreme mud terrain” tire, hence the name “X-MT.” This means they are shooting directly at the rock crawler/racer, overland, and show truck markets. This means these tires will be coming in sized up to 40-inches in diameter with rim sized from 17- to 20-inches. Currently, there are no 33’s nor are there any size tires for anything under the 17-inch rim unless the market makes demands for it. It can be produced, but it’s just not financially feasible when most mid-sized trucks come with 17-inch rims as standard and full-size trucks are 17- to 18-inches standard.

The tread design is very aggressive and is designed to work in the rocks despite being an MT tire. The shoulder and sidewall treads are not only designed to be pleasing to the eyes of someone who likes Sedona and Johnson Valley, but to grip on rock walls and boulders. The sipes cut into the tread blocks are mostly there for looks and will be worn away after 20- to 40-percent of tire life. Even so, the treads don’t exhibit terrible road noise. It is only available with black sidewall lettering on both faces.

Tread Compound

The tread compound was explained to be a new proprietary blend of rubber, polymers, and silica, but act like softer compound while lasting longer than a Nitto Mud Grappler, Micky Thompson Baja Claw, and even the legendary BF Goodrich Mud Terrain T/A KM2. The compound is also more cut and chip resistant than those tires. Under the compound are three nylon tread plies with a “three plus two” sidewall ply that wraps around the beads and crosses under the tread plies. Effectively, the X-MT is a six-ply tire because of the way the sidewall ply is done. Despite so many plies, the tires flex and still promote good road manners with a load range of E or D depending on tire sizing but all tires will have a Q speed rating.

Driving on the Edge of the Hammers

So, how did it do? My test vehicle was a Jeep TJ Wrangler 2.5-liter I4 with a five-speed owned by Cameron Harris. I’ll do a feature on his TJ in another article, but normally this truck wears a 38×12.50×17 and the Yokohama it was equipped with at the time of the test was the 40×13.50×17. With two more inches of outside diameter, at the maximum as tire sizes can vary between each manufacturer, the little TJ was struggling a bit but wasn’t complaining unless I didn’t give it enough gas. Driving along the flatter parts of Johnson Valley, the Wrangler was happy with fourth gear in high-range on the transfer case. In low range, it was best to start with third gear and climb up as necessary.

However, it was that low range where the Jeep did its best. While it wanted to drive at full throttle, it could climb with every trail that Tony threw at us. I couldn’t tell if I was more impressed with the TJ or the tires, either way I was left with a great feeling when I climbed out of it and handed it back to Cameron, so he could show what it could really do. Watching him drive over the features with a Yokohama employee from Japan was fun to watch as the guy wasn’t exactly prepared for what was coming. There were equal parts terror and excitement in his eyes as Cameron drove over boulders taller than the Geolandar itself.

Interesting Strengths

It was that moment that I was finally impressed with the tire. Normally, even the best tire needs to slip on the rocks for a moment to build up heat and soften the tread. This provides grip to get over stuff like that. The Geolandar, however, didn’t need it as much as I expected. Most of the rocks Cameron crawled over, the TJ just went. It had plenty of grip and went up Chocolate Thunder like it was powered by a bigger engine. When his dad went up in the tube chassis, four-wheel steer car, it acted like it didn’t care. It was only on the most extreme angles, where maximum tire grip is usually exceeded by driver bravado, was needed was where he had to let the tires rotate and heat up.

I got closer to the rock features as Tony went up in Terramoto that the tire surprised me again. For a new tire, literally mounted the day before they drove to Johnson Valley at the GenRight Shop, with so many plies in the sidewall, the tire flexed (Note: the rig pictured isn’t Terramoto, but “Yellowjacket,” which is basically Terramoto with a stock Jeep 3.6-liter V6). It looked like a tire that had been broken in weeks or months after it was mounted, and the belts had time to settle and loosen up.

In testing the Geolandar before this event, Tony said that this was normal, and the flex stayed about the same through the months he was able to use the tire prior to its official launch. This includes the DOT tires that Jordan uses on his 4400-rig, which still had plenty of tread life after seeing races in the King of the Hammers and the Mint 400.


Overall, the Yokohama Geolandar X-MT looks to be impressive on paper and in the brief practice I had with them during its debut launch. I hope they will release more sizes to fit more, older trucks that use 33s and smaller rims. I would like to test a set myself, but that will depend on you guys, so be sure to subscribe to Carbage so I can purchase a set from a dealer and begin testing on the Pathfinder. If you become an Annual or Biannual Subscriber, you can get Premium Content like galleries, videos, interviews, and more that Monthly and free users won’t get. Just like the gallery of the event, linked here.

Also, comment below if you guys want a feature on Yellowjacket, Terramoto, or any of the other GenRight built vehicles after Cameron’s TJ.

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2 thoughts on “A Test of the Yokohama Geolandar X-MT on the KOH Course

  1. Looking to buy a set of 40×17 inch tires for a Jeep crawler of mine. What’s is some pricing on a 40×13.5-17 or wider?

    1. Unfortunately, I don’t have pricing on the tires, but looking at other Geolandars in that size, expect the X-MT to be between $500 and $700 each. You should give your local tire dealer a call to find out how much it would be for you.

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