RokBlokz - GMC Sierra 2500/3500 2020+ Step-Back Mud Flaps

• OEM SPLASH GUARD DELETE KIT INCLUDED: Custom-designed Fender Trim caps included so you can delete the OEM splash guard and keep a streamlined, stylish look - adds a finished look to the fender's edge. $100 value!
• WORKS WITH BIGGER TIRES: Main brackets step back so the flap mounts behind the wheel well to allow for the biggest tire you can fit.
• EXTREME DURIBILITY: Designed to protect your Sierra HD truck in the harshest environments.
• FLEXIBLE (Not Floppy):  Bend and flex over any terrain but hold their shape at high speed for unsurpassed protection against mud, dirt and rocks.
• EASY INSTALL: With provided hardware and detailed instructions. 
• NO DRILLING: Most kits mount using existing OEM mounting locations.
• ASSORTED COLORS: Over 10 color options for ultimate personalization.
• PROUDLY MADE IN THE USA!
  

Please factor in 3-5 Business Days for Processing and Assembly.

WHAT'S INCLUDED:
Each RokBlokz mud flap set for the 5th generation Sierra 2500/3500 HD comes with 4 Flaps (Front and Rear), ROKBLOKZ Fender Trim cap kit, stainless steel & rust-resistant mounting hardware and instructions to fit factory hole locations. *Does require trimming of the fender to mount bracket and get the most clearance. 

WHAT IT FITS:
2020+ 5th Gen GMC Sierra 2500HD / 3500HD

DOESN'T FIT:
Not Confirmed for the GMC Sierra 2500 AT4X, AEV Edition
GMC Sierra 1500 
Any Chevrolet models or previous generations of GMC HD Trucks
Any other GMC Model or truck 

2 STYLES TO CHOOSE FROM:
-RALLY FLAPS were designed for those who like to keep a stock wheel set up but want some paint protection. If your tires rub, you will need our hi clearance step-back kit. 
-HIGH CLEARANCE STEP-BACK FLAPS mount inside the wheel well and step back past the fender for those who run lifts, larger tires and/or higher offset wheels that poke past the fenders and are tight on space inside the wheel well. SEEN ON THE TRUCK IN THE PHOTOS.

Please note that this kit was designed on a stock vehicle. When modifying fenders, wheels or suspension, you may have to modify the flaps to work with those changes. Please email us before ordering if you have any questions.

Please note that a shopping cart quantity of 1 = a whole kit (4 flaps)

CHECK OUT OUR OTHER GMC SIERRA HD ACCESSORIES HERE:

• Rokblokz Window Vents are a great accessory for getting airflow to the backseat while keeping bugs and dust out.

We are constantly making small improvements to our products, so yours might be a little different from what you see in photos and videos.

RokBlokz Step-Back Mud Flap Kit for 2020+ GMC Sierra 2500HD & 3500HD: Ultimate Protection and Style

Your 2020+ GMC Sierra 2500HD & 3500HD is built to haul, tow, and tackle tough terrain—but those wide, aggressive tires can throw rocks, mud, and road debris that chip paint and beat up your truck’s body. The Rokblokz Step-Back Mud Flap Kit is designed to stop the mess before it does damage, keeping your Sierra looking sharp while adding rugged functionality.

Built Strong for Real-World Use

Unlike thin rubber or brittle plastic flaps, Rokblokz are CNC laser-cut from our proprietary polymer blend. This material strikes the perfect balance of flexibility and rigidity—tough enough to take hits from rocks without cracking, yet firm enough to hold shape at highway speeds.

They won’t warp in scorching heat, crack in freezing temps, or fall apart under stress. Whether you’re running backcountry trails, towing heavy loads, or just driving daily, these flaps are made to perform in every condition.

And because the flaps are only as strong as what holds them on, our mounting brackets are built to last too. Made from stainless steel and finished with a two-layer powder coat, they’ve got double the protection against corrosion. The stainless underneath prevents rust, while the reinforced powder coat shrugs off chips and wear—so your setup stays solid season after season.

Sleek Fender Trim Cap for a Clean Finish

To tie it all together, the kit includes our Fender Trim Cap—a precision-fit piece designed to replace the bulky OEM splash guard trim. It creates a seamless, finished look while still protecting exposed edges when you pull the liner back for larger tires. No raw cuts or unfinished wheel wells—just a factory-clean appearance that matches your Sierra’s bold styling.

Key Features:

✔ Durable, Flexible Polymer – Resists cracking, warping, and fading
✔ Enhanced Protection – Shields paint, fenders, and undercarriage from rocks, mud, and spray
✔ Fender Trim Cap Included – Replaces OEM trim for a clean, finished edge
✔ Step-Back Design – Provides extra clearance for larger tire setups
✔ Heavy-Duty Mounting Brackets – Stainless steel with a dual-layer powder coat for maximum rust and chip resistance
✔ Easy Install – Uses factory mounting points with included stainless hardware
✔ Made in the USA – Designed, built, and tested for Sierra owners who demand more

Work Hard. Play Hard. Stay Protected.

Whether you’re on the jobsite, off the grid, or out on the highway, the Rokblokz Step-Back Mud Flap Kit with Fender Trim Cap is built to keep your Sierra 2500/3500 HD protected and looking good.

Protect your investment. Upgrade your Sierra with Rokblokz today.

Seeking Local Vehicles for Fitment Testing

At RokBlokz, we’re always looking for vehicles in or near Provo, UT to help us refine and perfect our mud flap designs. If you’re local and want to see if your vehicle qualifies, check out our list of needed models here. Participating owners receive special perks and the chance to be part of our design process!