2015 GMC Sierra Denali 3500 HD Extreme Towing Test [Ike Gauntlet HD]

2015 gmc sierra hd ike gauntlet extreme towing

TFLtruck presents the Ike Gauntlet HD extreme towing test, featuring the updated 2015 GMC Sierra Denali 3500 HD with the familiar 6.6L Duramax V8.  The luxurious Denali HD gets a fresh exterior and interior designs.  It takes the successful elements from the new generation light duty GM trucks and applies it to the Heavy Duty segment.  It makes for one of the quietest and most comfortable HD pickups we have ever tested.

This 6.6L turbo-diesel is unchanged and still produces 397 hp @ 3,000 rpm and maximum 765 lb-ft of torque @ 1,600 rpm.  Interesting note: the maximum rpm of the engine is 3,450 under power, and a whopping 4,800 rpm under braking.

2015 gmc sierra denali ike gauntlet extreme towing test video

The Heavy Duty version of the Ike Gauntlet is setup to test HD pickup trucks near their payload and towing capacities.  This configuration of the Sierra HD is rated at 4,264 lbs of payload.  And the specification sheet states that it can handle a maximum towing load of 13,000 lbs with a bumper pull or 17,100 lbs with a gooseneck or 5th-wheel.


Getting the front and rear axle load right is very important and we used the Certified CAT scale to check the load on each axle.  What is the damage?  Well, the 22,660 lbs GCWR was under the allowed maximum of 24,500 lbs.  This test pushed 92.5% of allowed Gross Combined Weight Rating.  The 4,740 lbs on the front axle was well within the maximum of 5,600 lbs.  The rear axle was loaded just 70 lbs under the max of 7,050 lbs.  The 2,400 lbs water tote in the bed should have been placed a few inches forward to shift some weight towards the front.  In the end, the 2015 Sierra HD was 220 lbs over the Gross Vehicle Weight Rating of 11,500 lbs.  One way to avoid this problem is to move our extra gear from the bed and into the trailer.

The 12,000 lbs trailer was pushing on the truck with 1,060 lbs of tongue weight.  This is very close to the estimated 10% trailer tongue weight.

How will it handle towing the heavy duty load up a mountain, near capacity, and at over 11,000 feet above sea level?

2015 GMC Sierra HD
Model 3500 Crew Cab 4×4
 As Tested $ $64,005
Engine 6.6-liter V8
Transmission 6-speed Allison
Power (hp / lb-ft) 397 / 765
Payload (lbs) 4,264
Tow Rating (lbs) 13,000 / 17,100 (3.73 axle)
Test Load (trailer + cargo + ppl) 15,000 lbs
Suspension Sag 3 in
Ambient Temp F 39F
Relative Humidity Low (25%)
Barometric Pressure (at top) 19.76 inHg
Calculated Power Loss 33.3 %
Down: Brake Temp (Front / Rear / Trailer) F 208 / 161 / 83
Down: Transmission Temp normal
Up: Time 7:52.55
Up: MPG 4.0
Up: Interior dB n/a
Up: Transmission Temp normal

Here is the full video of this Ike Gauntlet HD.



Andre Smirnov
Andre Smirnov

Andre Smirnov is a life-long automotive enthusiast, writer, reporter, and software engineer. He has been a contributor at TFL since 2011. When not working or spending time with the family – you can find him tinkering in the garage or simply ‘going for a drive’.