2018 GMC Sierra 3500 HD Base Max Towing Capacity & Payload
Max Towing Capacity
20,000 lbs
Safe limit: 16,000 lbs (80% rule)
Max Payload
5,955 lbs
Often the real limiting factor
Fuel Economy
10.5 mpg
9 city / 12 hwy (EPA Est.)
The 2018 GMC Sierra 3500 HD Base is rated to tow up to 20,000 lbs powered by the 6.0L. For real-world towing, the practical limit is 16,000 lbs — that's 80% of max, giving you margin for hills, headwinds, and load variation. The payload rating of 5,955 lbs is the number to watch closely — once you add passengers, hitch weight, and gear, it fills faster than most people expect. With this setup, you're looking at a great selection of travel trailers, toy haulers, and many fifth wheels.
Recommended Equipment
Towing Gear for This Truck
Matched to this trim's Class V hitch class and 20,000 lb tow rating
Class V Hitch Receiver
Required for towing. 2" receiver is standard on tow-equipped models.
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Trailer Wiring Adapter
7-pin to 4-pin adapters for trailer brake lights and signals.
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Brake Controller
Required by law in most states for trailers over 3,000 lbs.
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Weight Distribution Hitch
Strongly recommended for trailers over 6,000 lbs to level the load and reduce sway.
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Full Data
Specifications
Towing & Capacity
Engine & Performance
Dimensions
SpecificationValueShopLearn More
Towing
Payload & Weight
Curb Weight
7,045 lbs
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Engine
Engine
6.0L
Horsepower
360 HP @ 5400 rpm
Torque
380 lb-ft @ 4200 rpm
Transmission
6-speed shiftable automatic
Drive Type
Four Wheel Drive
Fuel Type
Flex-fuel (unleaded/E85)
Fuel Tank
36.0 gallons
Fuel Economy (EPA)
City9 mpg
Highway12 mpg
Combined11 mpg
Real-World (Fuelly, 28 owners)10.5 mpg
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Dimensions
Overall Length248.9"
Overall Width96.0"
Height77.6"
Cab Typedouble
What Can I Tow?
RV Class Compatibility
Based on a safe tow limit of 16,000 lbs and 5,955 lb payload. Shows what % of each RV class in our database you can tow.
RV Type
Weight Range
Coverage
Status
⚠ Vehicle capacity only — does not include passengers, gear, or tongue weight. Run the full calculator →
Compare Configurations
Other 2018 GMC Sierra 3500 HD Trims
| Configuration | Max Towing | MPG | |
|---|---|---|---|
| 2025 GMC Sierra 3500 HD Denali Ultimate 4WD | 20,000 lbs | 13.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Denali Ultimate 4WD | 20,000 lbs | 13.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Denali Ultimate 4WD | 20,000 lbs | 13.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro 4WD | 20,000 lbs | 13.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro RWD | 20,000 lbs | 11.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro 4WD | 20,000 lbs | 11.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro RWD | 20,000 lbs | 11.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro 4WD | 20,000 lbs | 11.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro RWD | 20,000 lbs | 11.1 mpg | View → |
| 2025 GMC Sierra 3500 HD Pro 4WD | 20,000 lbs | 11.1 mpg | View → |
Questions & Answers
Common Questions
How much can I actually tow with my 2018 GMC Sierra 3500 HD Base?
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The 2018 GMC Sierra 3500 HD Base is rated at 20,000 lbs maximum — but the real-world best practice is the 80% rule: target 16,000 lbs as your practical limit. This gives you margin for hills, headwinds, braking distance, and real-world load variance. More critically, check your payload first — the door sticker tells you your specific truck's limit, and payload may be your actual binding constraint.
What about payload — how much stuff can I put in the truck?
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You have 5,955 lbs of payload capacity — that's everything going IN the truck: passengers (~150 lbs each), camping gear, coolers, and critically the tongue weight from your trailer. For bumper pull trailers, tongue weight is typically 10–15% of the trailer's loaded weight. It fills up faster than most people expect, especially on longer trips.
What kind of hitch do I need?
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For the 2018 GMC Sierra 3500 HD Base, you need a Class V receiver hitch rated for 20,000 lbs. Don't skimp here — the hitch is the critical link between truck and trailer. For fifth wheel towing, you'll need a dedicated kingpin-style fifth wheel hitch mounted in the truck bed.
What types of RVs will work with my truck?
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With your 16,000 lb safe towing capacity, you're looking at a great selection of travel trailers, toy haulers, and many fifth wheels. The compatibility chart above shows what percentage of each RV class in our database you can handle. Use the Tow Calculator to check a specific RV including gear, water, and passengers.
What does GVWR mean and why should I care?
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GVWR is Gross Vehicle Weight Rating — the maximum your truck can weigh when fully loaded with people, gear, and fuel. Your truck's GVWR is 13,025 lbs. Exceed it and you're over-stressing brakes, suspension, and tires. This is different from towing capacity — it's about what the truck itself can carry.
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