How to Convert an M1101 to a 6x5.5 Bolt Pattern

One of the first modifications many M1101 owners make is replacing the massive military wheels with something that matches their tow vehicle.

The factory 8-lug wheels and 37-inch Goodyear MT tires are incredibly durable, but they’re also:

Extremely heavy
Expensive to replace
Difficult to balance
Overkill for most civilian use

Converting to a 6×5.5 bolt pattern opens the door to thousands of wheel and tire options while allowing many owners to share a spare tire with their truck or SUV.

Here’s everything you need to know before making the swap.

Why Convert to 6×5.5?

The 6×5.5 (6×139.7mm) bolt pattern is one of the most common light truck patterns in North America.

Vehicles that commonly use it include:

Toyota Tacoma
Toyota 4Runner
Toyota Tundra
Chevrolet Colorado
Chevrolet Silverado 1500 (older generations)
GMC Canyon
Nissan Frontier
Nissan Titan

This opens the door to many aftermarket off-road wheels as well as OEM.

Matching your trailer to your tow vehicle means:

One spare tire can serve both
Less weight
Lower replacement costs
More wheel choices
Easier tire availability while traveling – if you do have a flat on the road, finding a 37″ tire is going to be more challenging

Factory M1101 Wheel Specs

From the factory, the M1101 includes:

8-lug military wheels
37×12.50R16.5 Goodyear MT tires
Internal steel run-flat inserts
Hydraulic surge brakes
Heavy-duty 5,200-pound axle

The complete wheel and tire assembly weighs well over 150 pounds, making roadside tire changes a chore.

The Simplest Conversion

Fortunately, the axle itself does not need to be replaced.

Instead, most owners simply replace the brake drums/hubs with units drilled for a 6×5.5 bolt pattern while keeping the factory axle and surge brake system.

A commonly used replacement is the Dexter K08-201-97 hub and drum assembly, designed for 5,200-pound trailer axles with a 6 on 5.5 bolt pattern. It includes bearings, seals, a grease cap, and lug nuts, making it one of the easiest bolt-on conversion options.

Parts You’ll Need

Most conversions require, these will typically come as a kit:

Two 6×5.5 hub/drum assemblies
New bearings (if not included)
New grease seals
Grease caps
High-temperature wheel bearing grease
Cotter pins
New lug nuts

If your brakes need attention, this is an excellent opportunity to replace:

Brake shoes
Wheel cylinders
Brake hardware

Basic Installation

The conversion is surprisingly straightforward.

Safely support the trailer – I used the rear stabilizer legs and the front jack.
Remove the OEM wheels.
Remove the grease cap.
Pull the cotter pin.
Remove the spindle nut.
Slide off the original hub.
Inspect the spindle for wear.
Install the new greased hub.
Adjust bearing preload.
Install a new cotter pin.
Install the new grease cap.
Mount the new wheels.

Because you’re working with bearings and brakes, take your time and follow the manufacturer’s torque and bearing preload procedures.

Choosing Wheels

One advantage of converting to 6×5.5 is the huge variety of wheels available.

Popular sizes include:

16-inch
17-inch
18-inch

Common tire sizes include:

265/70R17
285/70R17
285/75R16
33×12.50R17

The right combination depends on your intended use and tow vehicle.

What About Offset?

Wheel offset matters.

Too much positive offset can reduce clearance to the suspension.

Too much negative offset increases bearing loads and widens the trailer.

Whenever possible, test-fit one wheel before purchasing an entire set. I took several measurements against the OEM wheel and then measured the wheels from my tow vehicle.

The Hub-Centric Challenge

This is where many conversions become more complicated.

Most trailer hubs are lug-centric, meaning the wheel is centered by the lug nuts.

Many OEM truck wheels—including Tesla wheels—are hub-centric, meaning they’re centered by the hub bore.

While a standard 6×5.5 trailer hub gets you the correct bolt pattern, the hub pilot may not fit your wheels. Unfortunately, this is a dimension that seems to be lacking from several manufacturers.

Should You Keep the Military Tires?

If your original tires are still in good condition, selling them can help offset much of the conversion cost.

Military wheels with run-flat inserts are still desirable for:

Restoration projects
Off-road builds
Military collectors
Export buyers

Is It Worth It?

For most civilian owners, absolutely.

The conversion offers several benefits:

Easier tire replacement
Reduced rotating weight
Better highway handling
Lower replacement cost
Shared spare tire with your tow vehicle
Huge aftermarket wheel selection

Unless you’re building a historically accurate military restoration, converting to 6×5.5 is one of the best upgrades you can make.

Frequently Asked Questions

Can I keep the factory surge brakes?

Yes. The hub conversion does not require changing the hydraulic surge brake system.

Do I need a new axle?

No. The factory axle can typically be retained when using compatible 5,200-pound hub and drum assemblies.

Can I use Toyota wheels?

Yes. Many Toyota wheels use the 6×5.5 bolt pattern. Just verify offset, center bore, and brake clearance before installation.

Can I convert my M1101 to electric brakes?

Yes, more to come on this later.

Can I use Cybertruck wheels?

Not directly. Although a 6×5.5 conversion solves the bolt pattern issue, Cybertruck wheels require an 84.1 mm hub-centric pilot, it seems most pilot hubs are too large and you will likely need adapters. More to come on this.

Final Thoughts

Converting an M1101 to a 6×5.5 bolt pattern dramatically increases your wheel and tire options while making the trailer far more practical for everyday use. Whether your goal is matching your tow vehicle, reducing weight, or improving serviceability, the conversion is one of the highest-value upgrades available.

Just remember that bolt pattern is only one part of the equation. Before buying wheels, verify offset, backspacing, brake clearance, and hub bore to ensure everything fits correctly the first time.

How to Convert an M1101 to a 6×5.5 Bolt Pattern