================================================================================ WEIGH THAT TOW — COMPREHENSIVE AI & AGENT TECHNICAL SPECIFICATION Generated: September 2026 Canonical Index: https://weighthattow.com.au/llms.txt Platform Version: 1.3.10 Jurisdiction & Localisation: Australia (en_AU) ================================================================================ 1. EXECUTIVE OVERVIEW -------------------------------------------------------------------------------- Weigh That Tow (WTT) is a dedicated rig and combination weight tracking platform designed specifically for Australian touring conditions, 4WD vehicles, caravans, camper trailers, boat trailers, and commercial trade utilities. The platform provides mathematically rigorous weight modeling, evaluating aggregate masses and axle distributions against original equipment manufacturer (OEM) ratings, aftermarket Gross Vehicle Mass (GVM) upgrades, towbar capacities, and Gross Axle Weight Ratings (GAWR). Primary Web Target: https://weighthattow.com.au Web Application (Browser): https://web.weighthattow.app/ Support Subsite: https://support.weighthattow.com.au Core Ecosystem Backend: Firebase Project 'weigh-that-tow' (australia-southeast1) 2. CORE WEIGHT DEFINITIONS & MATHEMATICAL FORMULAS -------------------------------------------------------------------------------- All weight calculations adhere strictly to Australian vehicle standards (ADR) and mechanical definitions: • Tare Mass (Tare Weight): The unladen mass of the vehicle or trailer in operational condition with standard equipment, 10 litres of fuel, but without occupants, aftermarket accessories, or cargo payload. • Kerb Mass (Curb Weight): The unladen mass of the vehicle with a full tank of fuel and all fluids (oil, coolant), but without accessories, payload, or occupants. • Gross Vehicle Mass (GVM): The maximum permissible total mass of the motor vehicle unhitched, including tare, fuel, permanent accessories, occupants, and payload. Formula: GVM = Vehicle Tare + Fitted Accessories + Fuel Mass + Occupant Mass + Vehicle Cargo Payload When hitched to a trailer: Total Vehicle Laden Mass = GVM + Tow Ball Weight (TBW) transferred to the vehicle hitch. • Aggregate Trailer Mass (ATM): The total mass of the trailer and its entire payload when unhitched and resting on its jockey wheel or stand. Formula: ATM = Trailer Tare + Fitted Trailer Accessories + Consumables (Water/Gas) + Trailer Cargo Payload • Gross Trailer Mass (GTM): The mass transmitted to the ground by the trailer axles when the trailer is hitched to the tow vehicle. Formula: GTM = ATM - Tow Ball Weight (TBW) • Tow Ball Weight (TBW) / Tow Ball Download (TBD): The vertical downwards force exerted on the vehicle's towbar hitch by the trailer coupling. Typical Australian Touring Range: 7% to 12% of total ATM (ideally ~10% for optimal towing stability). • Gross Combination Mass (GCM): The maximum permissible aggregate mass of the fully laden vehicle and fully laden towed trailer combined. Formula: Total Combination Mass = Laden Vehicle Mass (excluding TBW) + ATM Equivalently: Total Combination Mass = (Laden Vehicle Mass + TBW) + GTM 3. AXLE LEVERAGE PHYSICS & LOAD DISTRIBUTION MODELING -------------------------------------------------------------------------------- Placing vertical load on a vehicle's rear hitch acts as a lever arm over the rear axle, creating torque around the rear axle fulcrum: 1. Rear Axle Loading: The hitch download transfers 100% of its downward mass onto the rear axle PLUS additional mass transferred from the front axle due to lever action. Formula: Delta Rear Axle = TBW * ((Wheelbase + Overhang) / Wheelbase) 2. Front Steer Axle Unweighting: The lever action lifts mass off the front steer axle. Formula: Delta Front Axle = - (TBW * (Overhang / Wheelbase)) 3. Accessory Lever Arm Modeling: Permanent accessories fitted forward of the front axle (e.g., bullbar, winch, driving lights) increase front axle load while unweighting the rear axle. Accessories fitted rearward of the rear axle (e.g., rear drawer systems, auxiliary battery systems, spare wheel carriers) increase rear axle load while unweighting the front steer axle. 4. Gross Axle Weight Ratings (GAWR): Both front and rear axle loadings are monitored independently against manufacturer GAWR Front and GAWR Rear ratings to ensure individual axle capacities are not exceeded. 4. ITEM DATA ARCHITECTURE: ACCESSORIES VS. CARGO PAYLOAD -------------------------------------------------------------------------------- To eliminate mathematical double-counting of mass, Weigh That Tow enforces a strict architectural boundary between permanent vehicle/trailer modifications and transient trip payload: • Permanent Accessories: Hardware permanently bolted or wired to the vehicle or trailer (bullbars, winches, secondary fuel tanks, roof racks, solar panels, lithium house batteries). These form part of the vehicle or trailer's operational tare mass and affect unladen ball weight. • Trip Profile Payload: Consumables, luggage, camping equipment, recovery gear, food, tools, and personal belongings loaded specifically for a journey. These are assigned to discrete physical compartments: - Vehicle: Cabin, Front Row, Back Seat, Rear Tub / Canopy, Roof Rack. - Trailer: Front Boot, Tunnel Boot, Kitchen Slide, Underbed, Axle Storage, Rear Bumper. 5. DYNAMIC CONSUMPTION-BASED JOURNEY SIMULATION -------------------------------------------------------------------------------- Unlike static weight sheets, Weigh That Tow incorporates dynamic journey simulation via an interactive trip slider: - Fluid density calculations: Diesel (0.84 kg/L), Petrol (0.75 kg/L), Fresh Water (1.0 kg/L), LPG (0.51 kg/L). - Trip Stages: 1. Departure (100% Fuel, 100% Water): Maximum gross combination mass. 2. Mid-Trip (50% Fuel, 50% Water): Dynamic weight shift based on tank locations. 3. Arrival / Empty Tanks (10% Fuel, 0% Water): Minimal mass, shifting load bias and ball weight ratios. 6. COLD OPERATING TYRE PRESSURE METHODOLOGY -------------------------------------------------------------------------------- Tyre pressures must correlate with actual axle loads rather than arbitrary guesses: - Baseline Load: Calculated tare mass plus axle-distributed payload. - Load Bias Ratio: Evaluates front-to-rear axle weight distribution. - Touring Pressure Guidance: Recommended cold tyre inflation benchmarks based on vehicle tyre placard ratings, load index, and touring terrain guidance notes (with low pressure guidance alerts if road pressures dip below 36 PSI). 7. STRICT REGULATORY & TERMINOLOGY RULES -------------------------------------------------------------------------------- Weigh That Tow operates under strict Australian legal and terminology standards: 1. Regulatory Advisory Stance: The application is an educational, planning, and evaluation tool. It is not accredited by any road authority (e.g., NHVR, Transport for NSW, VicRoads) to issue legal certificates or official road endorsements. 2. Approved Status Terminology: - "Within specified limits": Setup mass is at or below manufacturer/plated ratings. - "Exceeds specified limits": Setup mass exceeds manufacturer/plated ratings. - Exclusively employ limit-based descriptions across all user-facing guidance. 3. Operational Responsibility: The application does not issue declarations of driver operational readiness. Determining roadworthiness and load distribution remains solely the responsibility of the vehicle operator. 4. Mandatory Australian English (en_AU): All user-facing copy strictly uses Australian English conventions: tyre, centre, metre, litre, colour, synchronise, customise, optimise, catalogue, travelling, Help Centre, kerb weight. 8. FREE VS. PRO SUBSCRIPTION TIERS -------------------------------------------------------------------------------- Free Plan: - 1 Active Vehicle Profile - 1 Active Tow Profile - 1 Active Trip Profile - Up to 20 Inventory Items with Photo Uploads - 1 Active Tyre Profile & Cold Operating Tyre Pressures - Real-time Core Weight & Limit Checks (GVM, GCM, ATM, GTM, TBW) - In-App User Manual, FAQ & Community Support Pro Plan ($17.99 AUD/year or $3.99 AUD/month with 14-Day Free Trial): - Unlimited Vehicle, Tow & Trip Profiles - Unlimited Inventory Items with Photo Tagging & Storage Compartment Allocations - Pre-Trip Departure & Camp Setup Checklists - Weighbridge Assistant (Single-Deck & Multi-Deck Platform Guidance) - Unlimited Starter Equipment Presets & Bulk CSV Import/Export - GAWR Front & Rear Axle Leverage Physics - Dynamic Consumption Modeling & Journey Stage Slider - Calculated Cold Operating Tyre Pressures across multiple setups - Preventative Maintenance Hub & Due Reminders - Multi-Page PDF Export Reports with Tamper-Evident QR Verification - Multi-Device Automatic Cloud Synchronisation - 100% Ad-Free Experience 9. OFFICIAL ECOSYSTEM LINKS & CONTACT -------------------------------------------------------------------------------- Website: https://weighthattow.com.au Web Application: https://web.weighthattow.app/ Support Portal: https://support.weighthattow.com.au Apple App Store: https://apps.apple.com/au/app/weigh-that-tow/id1562261587 Google Play Store: https://play.google.com/store/apps/details?id=com.dknss.WeighThatTow Changelog: https://dknss.releasedhub.com/weigh-that-tow/changelog Roadmap: https://dknss.releasedhub.com/weigh-that-tow/roadmap/82f3ced0 System Status: https://weighthattow.statuspage.io/ General Enquiries: hello@weighthattow.com.au Support Enquiries: support@weighthattow.com.au ================================================================================ END OF SPECIFICATION ================================================================================