Choosing a flatbed

Short answer: Pick the bed length from your truck's cab-to-axle (CA), the style from what you haul and tow, and steel or aluminum from how much payload you need to keep. Then add hitches and toolboxes.

Who this is for

Contractors replacing a pickup box with a flatbed
Dealers, lessors and fleets specifying cab-chassis units
Anyone towing a gooseneck who wants the bed and hitch to match

How to decide

Step 1: Measure cab-to-axle

CA is the distance from the back of the cab to the center of the rear axle. It sets the bed length, so the axle sits in the right spot under the deck. Measure on the truck, or read it from the window sticker or build sheet. The table below is a rule of thumb from CM's guide. We confirm on your VIN before we quote.

Your CA	Typical bed length	Common trucks
38–42"	84"	short-bed pickups
56–58"	8'6"	long-bed pickups
60"	9'4"	chassis cabs
84"	11'4"	chassis cabs
108"	13'	longer chassis cabs
120"	14'	longer chassis cabs

Source: CM Truck Beds Outfitter Guide and 2026 product book. Rule of thumb; we confirm fitment on your VIN.

Specs and weights are supplied by the manufacturer and may vary. Confirm details with VSI before ordering.

Step 2: Pick the style

CM's steel lineup covers most jobs. The RD is a plain flat deck. The SK adds skirts, fenders and four toolboxes built into the body. The SK Deluxe enlarges the two front boxes for drawer inserts. The ER hauler adds raised side rails and airline-track tiedowns. The TM tradesman adds a front utility box, a shovel box and a chain box for crews that tow every day. The HS hotshot is a lighter bed with a gooseneck and 5th-wheel rail system for long-haul towing.

If you mostly…	Look at
haul pallets and equipment, carry few tools	CM RD
carry tools and want them locked	CM SK / SK Deluxe
haul gear that needs side rails and tiedowns	CM ER
tow a gooseneck daily and carry tools	CM TM / TM Deluxe
run hotshot loads	CM HS
need the lightest bed	CM AL RD / AL SK / AL ER / AL TM
haul on a longer chassis	CM PL / AL PL platform (see flatbeds & platforms)

Step 3: Steel or aluminum

Steel costs less and takes abuse. Aluminum saves weight you can put back into payload. The gap is real: a CM RD 9'4" x 97" weighs 1,122 lb in steel, and the AL RD in the same size weighs 713 lb. That's about 400 lb more you can carry on every trip. If you run close to GVWR, aluminum often makes sense. If you drag steel and equipment across the deck all day, steel holds up better to that wear.

Step 4: Width and wheels

Single-rear-wheel (SRW) trucks usually take an 84" wide bed. Dual-rear-wheel (DRW) trucks take 94–97", so the deck covers the duals. Some CM models also come in 90" and 92". On most CM models, width changes weight by 20–90 lb.

Step 5: SD or GMSD

CM builds most beds in two versions. SD models include CM's SD headache rack. GMSD models are built for GM medium-duty trucks, with the GM medium-duty rack and 6" channel runners. They weigh more than the SD bed of the same length. Tell us the chassis make so we order the right one.

Step 6: Hitches

If you tow, decide now. Many CM beds come with a B&W gooseneck hitch with a welded ball and a rear B&W receiver hitch. The RD lists a 30,000 lb gooseneck and a 24,500 lb receiver. A turnover-ball option adds 5th-wheel use. The lowest rating in the chain sets your limit: the truck's GCWR, the hitch, the ball and the trailer coupler. The bed's hitch rating is not your tow rating.

Step 7: Deck and add-ons

RD and SK beds come with an 11-gauge steel tread plate deck. Options include a 3/16" heavy-duty deck, a gooseneck trough, drop-in or fold-down side rails, bale spikes, and wood, Rumber or Blackwood flooring. Underbody toolboxes, work lights, trailer plugs and a brake controller are easier to spec with the bed than to add later. We install them in the same visit.

Weight and payload

Every pound of bed comes out of payload. Base-model CM steel beds range from 887 lb (RD 84") to about 2,000 lb (TM Deluxe), and options add more. Payload is your truck's GVWR minus its curb weight, minus the bed, options, fuel, people and tools. Run the numbers before you choose, and we'll confirm them on your quote.

Example (base model)	Steel	Aluminum
CM RD 9'4" x 97" (SD)	1,122 lb	713 lb (AL RD)
CM RD 8'6" x 97"	1,048 lb	674 lb (AL RD)
CM RD 11'4" x 97" (SD)	1,256 lb	792 lb (AL RD)

Source: CM Truck Beds 2026 product book (base-model body weight; options, toolboxes and hitches add weight). Specs change; we confirm fitment and weights on every quote.

Specs and weights are supplied by the manufacturer and may vary. Confirm details with VSI before ordering.

Installing it right

CM's owner's manual calls for the headache rack to sit no more than 1-1/2" above the cab roof, with a 2" gap between the cab and the rack. We mount every bed to CM's instructions, move or add the lights and wiring, and set the hitch so it lines up with your trailer.

Fitment & payload: Bring your VIN or the window sticker. We confirm CA, width and hitch placement before we order. Payload calculator

Sources: CM Truck Beds 2026 product book (base-model lengths, widths, CA and weights); CM Truck Beds Outfitter Guide (CA to bed length), cmtruckbeds.com/outfitter-guide; CM RD one-pager, 08/10/2026; CM Truck Beds owner's manual (mounting).