Blog

The RAM TRX is the apex predator of the truck world. Out of the box, it’s a widebody monster with 702 horsepower and a stance that makes standard half-tons look like toys. But for many owners, the factory 35-inch tires leave too much gap in those massive flared fenders.

You want more rubber. You want a wider footprint. But you might not want to mess with the factory-tuned Bilstein BlackHawk e2 suspension. Leveling kits can change the ride quality or geometry of a truck engineered for high-speed desert running.

The question is simple: How big can you go on stock height? This is the DTX Performance guide to TRX fitment. No fluff. No guessing. Just the specs you need to build a legend.

Build for Authority: The TRX Baseline

Before you select your new setup, you have to understand what you’re working with. The TRX comes stock with 18x9 wheels featuring a +19mm offset. The factory tires are 325/65R18 Goodyear Wrangler Territory ATs, which measure out to roughly 34.6 inches tall and 12.8 inches wide.

Because the TRX is already 8 inches wider than a standard Ram 1500, you have more room to play with than your average truck. However, the inner wheel well and the suspension components are still the limiting factors. To push the limits, you need to master the relationship between tire width, wheel diameter, and offset.

Build for Scale: The 35-Inch Standard

If you want a "zero-fail" setup, the 35x12.50R18 or 35x12.50R20 is your safe bet.

When you stay within the 35-inch range but move to a wider tire or a more aggressive wheel, you gain a muscular stance without the risk of rubbing during hard compression. This is the setup for the guy who actually jumps his truck or hits the dunes at 60 mph.

The Conservative Specs:

• Tire Size: 35x12.50R18 or 35x12.50R20
• Wheel Width: 9" to 10"
• Offset: +18mm to +25mm
• Result: Zero trimming. Full suspension articulation. No rub at full lock.

Build for Impact: The 37-Inch Challenge

Can you run 37s on a stock TRX? Yes. But it isn't "plug and play" with every wheel combo.

Running 37x12.50 tires on the stock suspension is the most popular upgrade for the TRX. It fills the wheel well perfectly and gives the truck the scale it deserves. However, because the tire is nearly 2.5 inches taller than stock, the margin for error disappears.

To clear 37s without a leveling kit, the magic number is offset. If your wheels are tucked too far in (high positive offset), you will rub the frame or the suspension links. If they are pushed too far out (negative offset), you will shred your fender liners when you turn the wheel.

The Performance Specs for 37s:

• Tire Size: 37x12.50R18 (Recommended for sidewall)
• Wheel Width: 9"
• Offset: +12mm is the "Sweet Spot"
• Result: Minor plastic trimming may be required on the inner liner. Minimal rub at full lock.

Select the Strength: Weld Wheels for TRX

When you’re moving a 6,000-pound truck with 700+ lb-ft of torque, you don't put cheap wheels on it. You need wheels that can handle the rotational stress of 37-inch tires and the impact of off-road use.

Weld wheels are the industry standard for high-performance trucks. For the TRX, Weld offers forged and flow-formed options that provide the strength-to-weight ratio necessary to keep your unsprung weight down. This is critical because heavier tires already tax your braking and acceleration; you don't want your wheels adding unnecessary bulk.

Why Weld Wheels?

1. Precision Engineering: Weld designs wheels specifically for the high-load ratings required by the TRX.
2. Perfect Offsets: They offer the +12mm to +20mm offsets that are mandatory for fitting 35s and 37s on stock height.
3. Modern Muscle Aesthetics: Whether you want the classic look of the Weld Ledge or something more aggressive, these wheels define the "Modern Muscle" truck look.

Shop with confidence knowing that a set of Weld wheels is one of the few upgrades that actually matches the engineering quality of the TRX itself.

Select the Geometry: Offset and Backspacing Logic

If you’re shopping for wheels, you’ll hear these two terms constantly. Here is the no-nonsense breakdown for the TRX:

• Offset: This is the distance from the hub mounting surface to the center of the wheel. The factory +19mm offset keeps the tire tucked. Moving to a +12mm offset pushes the wheel out about a quarter of an inch. This is usually just enough to clear the 37-inch tire from the inner suspension components without causing major fender contact.
• Backspacing: This measures the distance from the mounting surface to the back edge of the wheel. For a 37-inch tire on a 9-inch wide wheel, you want to stay around 5.4 to 5.5 inches of backspacing.

If you go to a 0mm offset or a negative offset wheel on a stock height TRX, prepare to trim. You will likely hit the "pinch weld" area or the back of the front fender liner. For a clean, no-cut look, stay in the +12mm to +18mm range.

Push the Limits: Tire Choices for the TRX

Size is only half the battle. The tread pattern dictates how the truck feels on the pavement and performs in the dirt.

1. The All-Terrain Legend: Toyo Open Country A/T III

If you daily drive your TRX, this is the tire. It’s quiet on the highway but has the aggressive sidewall look that complements Weld wheels. In a 37x12.50R18, it’s one of the lighter options in its class, helping preserve your 0-60 times.

2. The Hybrid Beast: Nitto Ridge Grappler

The Ridge Grappler is the go-to for the TRX community. It bridges the gap between a mud-terrain and an all-terrain. It looks mean, handles the weight of the TRX well, and fits the +12mm offset Weld wheels perfectly.

3. The Desert King: BFGoodrich KO2

The KO2 is known for its durability. However, keep in mind that BFG tires often "run small." A 37-inch KO2 might actually measure 36.5 inches. While this might feel like you're getting "less" tire, it actually makes fitment on stock suspension much easier.

Select the Reality: What About the Spare?

Here is the truth most shops won't tell you: A 37-inch tire does not fit in the factory spare tire location under the bed without some serious effort (and even then, it’s a tight squeeze that may require deflating the tire).

If you commit to 37s on your Weld wheels, you have three options for the spare:

1. The Bed Mount: Use a Mopar or aftermarket bed-mounted tire carrier. It looks aggressive and makes the spare accessible.
2. The Chase Rack: Mount it high for that desert-racer look.
3. The Risk: Keep the factory 35-inch spare and hope you never need it. (Not recommended: running different tire sizes on an AWD system like the TRX can wreak havoc on your drivetrain).

Push the Build: Summary Cheat Sheet

Setup 1: The Daily Driver (Zero Rub)

• Tires: 35x12.50R20
• Wheels: Weld Ledge 20x9 +20mm
• Modifications: None.

Setup 2: The Modern Muscle Look (Maximum Meat)

• Tires: 37x12.50R18
• Wheels: Weld Performance 18x9 +12mm
• Modifications: Minor plastic liner heat-molding or trimming.

Setup 3: The Wide Stance (Trimming Required)

• Tires: 35x13.50R20
• Wheels: 20x10 -12mm
• Modifications: Significant trimming of the fender liners and potentially the pinch weld.

Build with DTX Performance

At DTX Performance, we don't just sell parts; we provide the blueprint for excellence. The RAM TRX is a precision machine, and your wheel and tire choice should reflect that. Whether you are looking for the weight savings of a forged wheel or the aggressive stance of a 37-inch tire, we have the inventory and the expertise to get it right the first time.

Don't guess on fitment. Don't settle for "good enough." Select the wheels that define the modern muscle era.

Shop Weld Wheels for your TRX today and build a truck that commands respect on every surface.

We promise to only send you good things: high-performance parts, expert advice, and the gear you need to stay at the front of the pack. If you have questions about a specific offset or tire brand, reach out to our team. We’re here to help you push the limits.

Shop with Confidence. Build for Power. Select DTX Performance.