We had a chance to test out some Yokohama Geolandar X-MT tires among the hammers in Johnson Valley. Following is our review.

Tires are specific, therefore, tires can be appropriate. Drivers should choose tires for their intended use. Tires that compromise and try to serve too many masters may fail to deliver at all. Having a tire that suits its intended use improves performance (off-road or on). Agreed?

In a few ways, tires are like shoes – engineered for specific function. You wouldn’t wear running shoes to go tap-dancing, but they’re great when you’re out for a scramble. In the same sense, combat boots might suck for a day at the beach (unless that beach is in Mogadishu), but they’re perfect when you’re climbing pointy rocks or hunkered down, lying in wait.

New Geolandar X-MT: Factory-Grade Aggressive

If the plan for your tires is to duke it out with rocks, bonking around in the pointy stuff, the new Yokohama Geolandar X-MT looks like it’s going to be a good tire for your trail rig or crawler. The X-MT is a targeted, aggressive maximum-traction tire that combines trusted construction with very duty-centric tread, produced by a manufacturer known for top-shelf niche products.

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Squint a little, and this new Yokohama’s staggered tread-block pattern looks a little like an old-fashioned paddle tire (though more evolved and complex), with significant lateral tread sections. This … focused … layout is supported by a tried-and-true light-truck carcass design (shared with the Geolandar M/T G003) and sidewalls built up to resist penetration and pinching.

The Geolandar X-MT’s tread block reaches about 2/5 down the sidewall (a characteristic popular on many trail and trial-poseur tires). Though it’s easy to brush off (figuratively), these sidewall-extended lugs have been shown to offer increased tractability at very low-pressure/high-deflection moments, and some manufacturers claim they also improve evacuation in water and sand.

The X-MT is initially targeted at big sizes, likely to center-mass of the dedicated crawling crowd: 35 to 40-inch diameter, 12.5 to 15.5-inch tread width, for 17 through 20-inch wheels. Of the amorphous load-range and ply settings, initial X-MTs are available in “D” and “E”-range eight and 10-ply units. These designations are always a grey area for ‘froaders, who can be notoriously choosy about what amount of flex and penetration is acceptable, and what sidewall behavior they can tolerate. Like we always suggest, find a trendsetter or leading-edge guy on trail who’s running a set of X-MTs on-trail and ask him about ‘em.

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The new X-MT uses a rubber compounds Yoko calls “triple-polymer”, which is purported to reduce the high-stress rubber tearing that appears as cutting and chipping on trail-worn tires. We’d be interested to see how uncut and unchipped a set of these are after a season in the rocks – this sort of evaluation requires time to tell.

Representatives of Yokohama stated that the new Geolandar X-MT’s design netted both surprising mileage and was surprisingly quiet on the road, unlike counterparts from other manufacturers. We asked “How surprising?”, and whether they were quieter by a measured degree or two, or enough so for legitimate daily-driven use? The folks from Yoko reaffirmed that you could actually have an in-car conversation while these tires were used at freeway speeds. Time will tell, though these are the sorts of assertions that a large manufacturer can’t afford to make in vain.

As the first X-MTs will be decidedly largish, the noise issue will need to be evaluated by others for now. We’ve inquired with the engineers and brand-managers for a narrower set of C-range 17-inch X-MTs for the independently suspended and skinny-trail crowd, which include a lot of trail-and-street 4Runners, FJ Cruisers, Tacos, Wranglers and XJs.

The Horrible Things We Do to Test Tires

So, you know of Johnson Valley by now (or you live under a rock, with your eyes closed and fingers in your ears): open four-wheeling terrain laid across the sun-baked sand-and-rock smorgasbord north of California’s Palm Springs zone (and up against the US Marines’ expansive base at Twentynine Palms). Johnson Valley offers great crawling, lots of trails and is home to the King of Hammers race. It’s good stuff. The Yokohama team put their new Geolandar X-MT in the hands of long-time Johnson Valley fan, Hammers competitor and GenRight founder Tony Pellegrino, and asked that his crew abuse the new tire for a spell. Pellegrino agreed. Off-Road.com was there.

We had the opportunity to drive the X-MT on trail-prepped Jeeps and Jeep-like rigs. Ironically, because the trucks and trail buggies provided by the GenRight crew were so thoroughly prepared for trail and rock use, the tires proved to be very capable. Where the prepped buggies’ capabilities ended and the tires’ began was harder to define. However, all the suspension articulation in the world couldn’t have compensated for a tire that wouldn’t deliver.

We found that aside from their unflinching traction and relative predictability compared to some balloon-based bias-plies often found in the rocks and sand, the Geolandar X-MT went about its business without drama. In heavy sand, a little bit of throttle went a long way to make them bite.

It was during the afternoon runs when the journalists were kicked out of their seats and replaced by the pros from GenRight (and the buggies were pounded through Hammers favorites like Chocolate Thunder and Sledgehammer), that the X-MTs really shined. Because the tire is spec’d to be capable as a 10/10ths trail tire, it took 10/10ths trail to show them at their best.

We kept a close eye for cases of sidewall pinching in the Hammers features, and there was no shortage. This is one of your authors’ rock-tire bugaboos, him having ruined several in this fashion because of separation of the sidewall plies or cuts at the rim. Back at HQ, we noted no instances of sidewall breakdown despite the abuse.

The Verdict: Yokohama Geolandar X-MT Tire Review

We’re of the belief that an element of this tire’s success will be that it’s not so obliged to trail use that it’s untenable in basic driving. Yokohama was willing to put very robust lug patterns on a production tire structure for on-trial use in heavy rocklike terrain, but didn’t compromise on essential structural characteristics that make the Geolandar X-MT’s more streetable relatives like the M/T G003 a commercial success.

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A note to Off-Road.com fans and readers: the tire companies are very good at putting journalists in a position to enjoy their tires. They host events in cool places, they surround you with interesting, experienced people, and they position their products in an environment that suits them. Our job, as your experts, is to relate to the manufacturer, learn about the tire, and most importantly, use the opportunity to observe the product at the edge of its design envelope. This goes for new cars, new tires, or new parts. This writer has been disinvited by manufacturers because he took a position on a product that its maker didn’t like: honesty is the best policy, but it doesn’t make as many friends. We do it for you.

Photos by Yokohama and Justin Fort