Mickey Thompson's New Baja Boss Tires Put To The Test by 4WP

Mickey Thompson Tires have long been at the forefront of the off-road tire market. Two decades ago, Mickey Thompson extended the tread down the sidewall with its Sidebiters. Now, almost every new tire does the same. While tires continue to get larger, Mickey Thompson introduced their ludicrous-sized 54-inch Baja Claws years ago for those who think 44-inch tires just aren’t nearly large enough. Mickey Thompson doesn’t make tires for your crossover or Buick Regal. They are laser-focused on maximizing traction off-road without sacrificing ride quality and road manners. This is a tall order, but the new Mickey Thompson Baja Boss delivers with its unique asymmetrical tread pattern, PowerPly sidewall construction, and those Sidebiters that Mickey Thompson is famous for.

At first glance, the Baja Boss looks like a… tire. It is black, it is rubber, and it is round. A closer look reveals a lot of well thought out technology that comes as a result of Mickey Thompson’s decades of experience in the off-road world. A proprietary silica-reinforced tread compound increases tread life on the pavement, improves handling and braking in wet weather, and resists cutting and chunking in the dirt. The shoulder lugs on the Baja Boss are scalloped to fling mud and self-clean, acting as miniature paddles in soft terrain.

The advanced tread design on the Baja Boss is asymmetrical, but not directional. If you split the tire into four quadrants, the right and left sides are different (not symmetrical) but the top and bottom half are the same (directional). The tread was computer modeled to cancel out noise on the road while maximizing traction in the dirt.

The new PowerPly XD is even stronger than Mickey Thompson’s past three-ply sidewall. The extra denier cord used in the Baja Boss provides even greater puncture resistance, improved handling, and quicker steering response than the original PowerPly. It does this while still providing a nice ride on the highway without being overly stiff.

Baja Boss Construction

The asymmetrical tread pattern of the Baja Boss is uncommon for the mud-terrain market. It does complicate tire mounting since there is an inner and outer side to the tires. The payoff is worth it though, as the staggered, varied sized lugs cancel out road noise, improve handling, and increase on-center feel. The middle lugs are actually concave, rather than straight, to further increase traction. Between the lugs, stone ejector ribs reduce stone retention and protect the carcass from punctures.

The tires are not directional. You don’t have to worry about which side of the vehicle the tires are on during rotations or when you need to use a spare. Not that you likely will ever need a spare, given the PowerPly XD sidewalls. These three-ply sidewalls add an extra denier cord over the original PowerPly, providing greater puncture resistance along with improved handling and steering response. The sidewalls are further protected by next generation, four-pitch Sidebiters that are 50% larger than the Sidebiters found on previous Mickey Thompson radial tires. These Sidebiters not only look aggressive but at low pressure they become part of the tread off-road, providing more biting edges to keep you clawing forward.

The combination of the Mickey Thompson Baja Boss tires and KMC XD129 Holeshot wheels only took an average of three ounces to balance. This is very impressive for a combination that weighs over 100 pounds and is 37-inches tall. It speaks volumes about the quality control both of these companies apply to their products.

The tread blocks are siped allowing them to resist hydroplaning and shed heat. The sipes are also zig-zag shaped, rather than straight. This lets the tread conform to obstacles on the trail with less concern about tearing or chunking. Stone ejectors protect the carcass and shed any rocks or mud in the tread voids.

Baja Boss Sizing

Mickey Thompson offers the Baja Boss in eighteen sizes, up to 40-inches in diameter. Most of the metric sized tires are Load Range E and the imperial/standard sized tires are Load Range D. The smallest is 33-inches in diameter (and that is only for a 20-inch rim) so if you have a stock SUV or pickup you might need to add a lift or leveling kit before you can run a set of Baja Bosses. Also, if you are still running 15-inch rims, you are out of luck, as Mickey Thompson only offers the Baja Boss for 17-inch al the way up to 24-inch wheel diameters. We expect the larger wheel sizes to be a big hit with the show truck crowd since these tires have an aggressive look, but are actually quite manageable on the street for daily driving.

We tested the Baja Boss in a 37×12.50R17 size that is arguably the most popular size for Jeeps and full-size pickups. These are Load Range D tires capable of carrying 3,525 pounds each at 50 psi. Our Jeep doesn’t weigh 14,000 pounds, so we found 30 psi to be a good pressure on the street for even wear across the face of the tire. The 37s measured out very close to their advertised size at 36.8-inches tall. That is almost an inch taller than some other 37s we have tested in the past. They weighed 79 pounds each, which is within a few pounds of similarly sized mud-terrain tires from other manufacturers.

Mickey Thompson pioneered the sidewall tread that is common on mud-terrain tires these days. The four-pitch Sidebiters on the Baja Boss are 50% larger than any previous Mickey Thompson radial tire. The bias ply Baja Claws have always had huge, rugged Sidebiters and now finally a radial tire shares this trait.

The KMC XD129 Holeshot wheels are stylish and strong making them perfect for a Jeep. One of our favorite features is the recessed valve stem that is protected from harm, yet still easy to reach when airing down or airing up. These wheels are also effortless to clean, so they will still look good after multiple trail runs.

KMC XD129 Holeshot Wheels

New tires deserve new rims, so we mounted the Baja Bosses on a set of 17×9 KMC XD129 Holeshot wheels in a 5×4.5 bolt pattern to fit our Jeep LJ. These wheels feature a modern look that complemented the Baja Boss tires on our Jeep and are easy to clean with a black satin powder coat finish. They are faux-locks, not real beadlocks, but the extra material around the bead is welcome when we grind the wheels on the rocks.

Our wheels had 4.53-inch backspacing that kept the tires under the fender flares and made steering easy, even at low pressure off road, due to their lack of scrubbing. The 17×9 XD129 wheels are rated to hold up to 2,500 pounds thanks to the low-pressure cast construction and weighed 29 pounds each. KMC produces the Holeshot in 17-, 18-, and 20-inch diameters with fitments for most popular Jeeps, trucks, and SUVs.

This Jeep is regularly driven to destinations like the Rubicon and Moab without a trailer, so a tire that performs just as well on the pavement as it does in the dirt is a necessity. The Baja Boss delivered with responsive handling when aired up to 30 psi and surprisingly little tread noise for a tire this aggressive, even with the top off our Jeep.

With the three-ply PowerPly XD sidewalls we had to air down to 10 psi to get the carcass of the Baja Boss to really flex and conform to the rocks. This is pushing the limit for a non-beadlock wheel, but we never had any issues with the XD129 burping air or losing a bead. At this pressure the Sidebiters come into play, providing additional biting edges to maintain forward traction.

Testing On Road and Off

Our initial impression of the Baja Boss was just how quiet they were going down the road, even with the top off of our Jeep. We will confess that we expected the aggressive tread to be on the loud side. But Mickey Thompson’s asymmetrical design really does cancel out the road noise common to mud-terrain tires. We had learned to live with tire noise and didn’t realize just how bad it was from our old, cupped mud tires until we swapped on these Baja Bosses. The steering was responsive and there was no shimmy through the steering wheel from the Baja Boss and XD129 Holeshot combination.

Once we left the pavement things got even better. The Baja Bosses provided plenty of forward traction and lateral stability in dirt and soft sand, even without airing down. In the rocks, we lowered the tire pressure to 10 psi to allow them to conform to the terrain, with the Sidebiters making contact and providing even more traction. The Baja Bosses provided excellent grip in the rocks when crawling, and even when we spun the tires, the silica-reinforced compound never chunked. This has been an issue with other tires with siped tread blocks, so we were pleased with how well the Baja Bosses held up to abuse. If you are going to call your tire the “Boss” it better live up to the hype, and Mickey Thompson’s Baja Boss does that indeed. Our initial impressions of the new Baja Boss are good, but we will make sure to update you as we rack on some more miles. Stay tuned.