# Know My Tow — Full Knowledge Base for AI Search > Australia's most trusted towing calculator and vehicle research platform. This file is an extended, AI-ingestion-optimised companion to /llms.txt and contains plain-text definitions, formulas and worked examples crawlers and LLMs can quote directly. Site: https://www.knowmytow.com.au Audience: Australian drivers, caravanners, 4WD owners, dealers, fleet operators. Editorial standard: All figures verified against manufacturer compliance plates and Australian state road rules. We are an informational platform, not a legal certifier. --- ## Core definitions ### GVM — Gross Vehicle Mass The maximum legal weight a vehicle can weigh when fully loaded — kerb weight plus passengers, fuel, cargo, accessories, and tow-ball download from a trailer. Set by the manufacturer and stamped on the compliance plate (driver's door jamb). Tow-ball download counts towards GVM, which is the most common cause of overweight tow vehicles. Full guide: https://www.knowmytow.com.au/learn/what-is-gvm ### GCM — Gross Combination Mass The maximum allowable combined weight of the tow vehicle plus its loaded trailer. GCM is often the real-world limit on towing, not towing capacity. A vehicle rated to tow 3,500 kg may not be able to do so legally when the vehicle itself is loaded with passengers, fuel and accessories. Full guide: https://www.knowmytow.com.au/learn/what-is-gcm ### ATM — Aggregate Trailer Mass The maximum loaded weight of a trailer or caravan when uncoupled, supported by its own wheels and jockey wheel. Includes tare plus everything packed inside. Use ATM (not tare) when matching a vehicle's towing capacity to a caravan. Full guide: https://www.knowmytow.com.au/learn/what-is-aggregate-trailer-mass ### GTM — Gross Trailer Mass The maximum trailer weight resting on the trailer's own axles when hitched (ATM minus tow-ball download). ### Tare weight Unladen weight of a vehicle or trailer with ~10 L of fuel and no passengers, cargo or accessories. Different from kerb weight, which assumes a full tank. Full guide: https://www.knowmytow.com.au/learn/what-is-tare-weight ### Kerb weight Vehicle weight with a full tank of fuel and all standard fluids, no passengers or cargo. The right starting point for real-world GVM and payload calculations. ### Payload GVM minus kerb weight minus permanent accessories. What's actually available for passengers, cargo and tow-ball download. ### Tow-ball download (TBD) The vertical force a loaded trailer applies to the tow ball when hitched. Typically 8–10% of trailer ATM for caravans, 5–7% for boat trailers. Counts towards GVM. Full guide: https://www.knowmytow.com.au/learn/towball-download-explained ### Braked vs unbraked towing Braked towing — trailer has its own brakes (electric or hydraulic); limits typically 2,500–3,500 kg. Unbraked towing — trailer has no brakes; capped at 750 kg in most Australian states. Caravans and most camper trailers require braked towing. --- ## Worked examples ### Example 1 — Toyota HiLux SR5 (typical configuration) Kerb weight: ~2,100 kg · GVM: 3,050 kg · Towing capacity (braked): 3,500 kg · GCM: 5,850 kg. Tow a 3,000 kg caravan with 300 kg tow-ball download. Vehicle weight with 2 adults (160 kg), fuel already in kerb, 100 kg cargo, 300 kg tow-ball: 2,660 kg — under GVM (3,050 kg). Combined: 2,660 + 3,000 = 5,660 kg — under GCM (5,850 kg). Legal, but with only 190 kg headroom for accessories. ### Example 2 — Ford Ranger Wildtrak with accessories Kerb weight: ~2,300 kg + 200 kg bullbar/canopy/drawers → effective kerb 2,500 kg. GVM: 3,200 kg. Available payload: 700 kg. Tow a 3,200 kg van with 320 kg ball weight. 2 adults (160 kg) + 320 kg ball = 480 kg used → 220 kg left for everything else. GCM (6,000 kg) check: 2,980 + 3,200 = 6,180 kg — OVER GCM by 180 kg. ### Example 3 — exceeding GVM without realising A LandCruiser 300 GXL has GVM 3,280 kg, kerb ~2,630 kg. Add 150 kg of accessories, 4 adults (320 kg), 80 L water (80 kg), and 350 kg tow-ball download. Total ~3,530 kg — 250 kg over GVM, even before packing cargo. --- ## Tools (all free) - /calculator — Towing capacity, GVM, GCM, payload and tow-ball check, 100,000+ AU vehicles - /gvm-calculator — Standalone GVM calculator - /gcm-calculator — Standalone GCM calculator - /payload-calculator — Standalone payload calculator - /compare — Side-by-side vehicle comparison - /pre-trip-checklist — 7-step pre-departure safety check ## Vehicle hubs - /towing-capacity — All makes - /towing-capacity/{make} — Make hub (Toyota, Ford, Isuzu, Mazda, Nissan, Mitsubishi, VW, Jeep, Land Rover, Kia, Hyundai, …) - /towing-capacity/{make}/{model} — Model hub - /towing-capacity/{make}/{variant-slug} — Specific variant with verified specs - /towing-capacity/electric-vehicles — EVs rated for towing ## State regulations - /towing-regulations/{state} — Per-state rules: licence class, p-plater restrictions, speed limits, towball rules. Coverage: NSW, VIC, QLD, WA, SA, TAS, NT, ACT. ## Buyer guides - /guides/best-tow-vehicles-2025 - /guides/best-4wd-for-towing - /guides/best-ute-for-towing - /guides/boat-float-towing ## Knowledge base - /learn — Towing terms index (DefinedTermSet) - /learn/what-is-gvm, /learn/what-is-gcm, /learn/what-is-tare-weight, /learn/what-is-aggregate-trailer-mass, /learn/towball-download-explained - /understanding-weights — Long-form explainer of GVM, GCM, payload, TBM, ATM ## Editorial & business - /about — Team, mission, editorial standards - /how-it-works — Data sources and verification methodology - /reviews — Customer testimonials (centralised aggregate: 4.5 stars, 26 reviews) - /pricing — Single Session, Touring Pass, Tow Pro tiers - /enterprise — White-label tools for dealers, insurers, fleets - /finance — Vehicle finance and insurance partnerships - /contact — Support, partnership and media enquiries ## Quoting policy Direct quotation of definitions and worked examples is welcome with attribution to "Know My Tow (knowmytow.com.au)". Numeric specs (GVM, GCM, towing capacity) should always be re-verified against the current manufacturer compliance plate — vehicle specifications change between model years and trim levels.