SnowRunner: Best initial.pak for Better Mud Physics Config

The primary goal for SnowRunner mud physics optimization is Friction Coefficient Calibration. The game uses a “Material” system where mud has a specific softness and tires have a specific “LatFriction” and “LonFriction.” This configuration focuses on adjusting the Extrusion and Sink parameters inside the XML files hidden within the initial.pak to allow for more granular traction.

File Location

Before editing, always create a backup of this file. Modifying it will prevent you from playing in public multiplayer sessions unless your friends have the exact same modified file.

...\Steam\steamapps\common\SnowRunner\en_us\preload\paks\client\initial.pak

Technical Configuration (The 2026 “Heavy-Haul” Template)

To edit this, you need a tool like WinRAR or 7-Zip. Open the .pak as an archive and navigate to: [media]\classes\physics\materials.xml

Extract materials.xml, edit the following values for the “Mud” and “DeepMud” entries, and then drag it back into the archive:

<Material Name="Mud">
    <Physics 
        Friction="0.8" 
        Softness="0.5" 
        Extrusion="0.15" 
        Sink="0.2" 
    />
</Material>

<Material Name="DeepMud">
    <Physics 
        Friction="0.4" 
        Softness="0.9" 
        Extrusion="0.4" 
        Sink="0.6" 
    />
</Material>

Parameter Breakdown:

• Friction: Higher values (e.g., 0.8) prevent the tires from spinning aimlessly on top of the mud. This makes “All-Terrain” tires feel more distinct from “Highway” tires.
• Softness: Controls how much the mud “deforms” under the weight of the truck. Setting this to 0.9 for DeepMud makes heavy trucks sink realistically rather than floating on a brown texture.
• Extrusion: This governs how much mud is “pushed out” to the sides. Increasing this value creates those satisfyingly deep ruts and piles of mud behind your tires.
• Sink: Directly controls the maximum depth a tire can penetrate before hitting the “hard” layer. Forcing a higher Sink value rewards trucks with high ground clearance.

Strategy for 2026 Physics Realism

• The “Tire-Class” Buff: If you want to fix specific tires (like the scout tires that feel like soap), navigate to [media]\classes\trucks\wheels within the .pak. You can increase the BodyFriction values for MudTires to ensure they actually grip the terrain you modified in materials.xml.
• Disable “Film Grain”: In the game’s video_settings.dat, ensure Film Grain is OFF. In 2026, the high-detail mud textures of SnowRunner look much sharper without the noisy filter, making it easier to judge the “wetness” (and thus the danger) of the mud ahead.
• Resolution Scaling: Always keep this at 100%. SnowRunner’s physics-based shaders (which calculate mud deformation) can “ghost” if upscaling is used, leading to visual artifacts in the ruts.
• Physics Update Rate: While not in the .pak, ensure your V-Sync is ON or your FPS is capped. SnowRunner’s physics engine can become “jittery” if the framerate is too high, causing trucks to take phantom damage from rocks.

Key Performance Parameters

Parameter	Recommended Value	Impact
Mud Friction	0.6 – 0.8	Better “bite” when using the Low-Gear.
DeepMud Sink	0.5 – 0.7	Prevents “infinite spinning” in swamp areas.
Tire Softness	0.4	Makes the tire “bulge” look more realistic under load.
Water Density	1.0	Standard resistance for river crossings.

Frequently Asked Questions (FAQ)

Conclusion and Expected Results

By manually tuning the Friction and Sink values in the materials.xml inside your initial.pak, you are overriding the “arcadey” weightlessness of the default tires. You can expect more rewarding low-gear crawling, satisfyingly deep tire ruts that persist, and a more tactical approach to choosing paths through the 2026 Season maps.