01 What makes it unique
The 3915TB is the biggest Montana profiled here and the one that solves the single hardest problem in a shared fifth wheel: bathrooms. It is one of the few fifth wheels on the market with two full bathrooms — not a bath-and-a-half, but two complete baths — with the second served by its own dedicated second entry door. A middle bunkroom with a loft above it sits between the baths and the private rear bedroom, making it a true family-and-guests coach at 43 feet.
Its capacities are scaled to match. The 3915TB carries a 137-gallon grey tank and a 98-gallon black tank — by far the largest holding tanks of the profiled plans, sized for the second bathroom and extended stays — on the standard luxury build of a 12-inch z-frame chassis, walkable Alpha TPO roof, Four-Season package and La-Z-Boy furniture, with a king bed, a 50-inch living-room TV and a single 15,000-BTU Coleman Mach heat-pump air conditioner standard. RVUSA and multiple dealer records agree on a 15,222-pound dry weight and the line’s 18,000-pound GVWR, with a 2,780-pound dry pin and a 2,778-pound payload.
At an MSRP of $137,228 it is among the most expensive plans in the luxury line, and at 43 feet with two baths it is firmly full-size fifth-wheel territory needing a properly rated heavy-duty truck. For a large family, or anyone who routinely travels with guests and refuses to share one bathroom, the two-full-bath 3915TB is the flagship of the profiled Montana lineup.
02 Full specifications
Dimensions
- Exterior length
- 43' 0"
- Exterior width
- 8' 0"
- Exterior height
- 13' 4"
- Interior height
- 7' 0"
Weights
- Dry / unit base weight
- 15,222 lbs
- GVWR (max loaded)
- 18,000 lbs
- Net cargo / payload
- 2,778 lbs
- Dry pin weight
- 2,780 lbs
Capacities
- Fresh water
- 70 gal
- Grey water
- 137 gal
- Black water
- 98 gal
- Refrigerator
- 18 cu ft
Construction
- Frame
- 12" I-beam · z-frame
- Walls
- 2" laminated fiberglass · lauan
- Roof
- Alpha TPO · walkable, 5" rafters
- Underbelly
- Four-Season · heated, 0° tested
Running gear
- Axles
- 2 (tandem)
- Hitch
- Fifth-wheel (in-bed)
- Suspension
- MORryde® CRE3000 · wet bolts
- Cooling
- Coleman Mach 15K · 50A
Galley & bath
- Cooktop
- 3-burner recessed
- Refrigerator
- 18 cu ft
- A/C
- 15K Coleman Mach heat-pump (triple-15K opt)
- Water heater
- Quick-recovery · gas/electric
Sleeping & layout
- Sleeps
- 6
- Slides
- 4
- Hitch type
- Fifth-wheel (in-bed)
- Primary bed
- King
Drawn to scale
Weight budget
Size, with end view
Holding tanks
Axles, wheels and nose shape are schematic; not a floorplan. Data: dataset.
Towing it
Loaded range: 15–25% of GVWR on the pin, a rule of thumb, not a measurement of this unit. No truck ratings or hitch classes (why; NHTSA, DOT HS 809 433). The range starts at the published dry figure, because loaded is never lighter than dry.
03 The Montana floorplan family
Montana is Keystone’s luxury fifth-wheel line. The line runs to fifteen floorplans for 2026; the six highest-demand layouts are profiled here in full, and the rest — along with the lighter, lower-profile Montana High Country sub-line — are catalogued on the line hub. The 3915TB on this page is highlighted; each other profiled plan links to its own page.
| Floorplan | Nominal | Sleeps | Notable |
|---|---|---|---|
| 3123RL | 35 ft | 4 | Rear-living entry, kitchen island |
| 3100RL | 36 ft | 4 | New-2026 widebody, rear-living couples |
| 3231CK | 37 ft | 4 | Rear living, kitchen island + dual pantries |
| 3531RE | 39 ft | 4 | Rear entertainment, glass-door pantry |
| 3532SP | 39 ft | 4 | Side patio, king bed, theater seating |
| 3795FK | 40 ft | 6 | Front raised kitchen, rear full bath, sleeps 6 |
| 3623EB | 40 ft | 4 | Rear living, bike garage, four slides |
| 3761FL | 41 ft | 6 | Front living, bath-and-a-half, 5 slides |
| 3781RL | 41 ft | 4 | Rear living, kitchen island |
| 3857BR | 41 ft | 8 | Middle bunkroom + loft, family |
| 3901RK | 42 ft | 4 | Rear kitchen, bath-and-a-half, front master |
| 3915TB | 43 ft | 6 | Two full baths, bunkroom + loft |
| 3941FO | 43 ft | 6 | Front office full-timer, outside kitchen |
Montana is Keystone’s luxury fifth-wheel line. The full line runs to fifteen floorplans for 2026, plus the lighter, lower-profile Montana High Country sub-line catalogued separately on the hub. Body specifications (lengths, heights, payload, tanks, refrigerator, sleeping, slides and A/C) are RVUSA-verified against the 2026 structured spec records, each page matched to its RVUSA floorplan record by code and title; pin (hitch) weights are from the same records. Montana publishes a 18,000-pound GVWR across the luxury line; the lighter three-slide 3123RL entry carries a derived 16,580-pound GVWR, and the new widebody 3100RL has its dry weight and GVWR flagged as derived. Real loaded pin weights run higher — always weigh the loaded coach and confirm against your truck's payload and rear-axle ratings.
04 Notes on this floorplan
Two full bathrooms
Not a bath-and-a-half — two complete baths, the second with its own entry door — a rare and sought-after fifth-wheel feature.
Largest holding tanks
137-gallon grey and 98-gallon black — by far the biggest tanks of the profiled plans, sized for the second bath and long stays.
Family-and-guests flagship
A 43-foot middle-bunkroom-and-loft plan between two baths and a private rear suite — the most accommodating profiled layout.
Full-size truck required
At 43 feet and the line’s 18,000-lb GVWR, this is heavy-duty-truck territory — confirm payload and rear axle on a 3/4- or 1-ton.
05 How it compares
The lighter family plan — the same bunkroom-and-loft idea with one bathroom, shorter and a touch more payload.
The full-timer alternative — trades the second bath for a front office and an outside kitchen at a similar size.
Grand Design’s flagship fifth wheel — the natural luxury cross-shop against the largest Montana plans.
06 Loading it for a trip
A full 70-gallon fresh tank is about 584 lb of water (water counts as cargo: 49 CFR 571.120 S10.4.2), 21% of the 3915TB’s 2,778 lb cargo capacity, leaving 2,194 lb (366 lb per rated berth). Across 13 Montana floorplans the water share runs 15% to 28%, and 4 give up more than this one. Nearest on that share: Montana 3761FL at 19% and Montana 3623EB at 23%. Your own unit’s figure is on the label inside its entry door (49 CFR 571.120 S10.4.3).
07 Where this floorplan sits
Closest sibling: the Montana 3761FL, nearest on the published figures. It differs on 6 of the 9 fields both publish (this plan first): length 43 ft 0 in vs 41 ft 0 in; dry weight 15,222 lb vs 14,951 lb; cargo capacity 2,778 lb vs 3,049 lb; dry hitch weight 2,780 lb vs 2,880 lb; grey tank 137 gal vs 88 gal; black tank 98 gal vs 88 gal. They match on sleeps, GVWR and fresh tank.
| Montana plans | This plan | Position, low to high | Range |
|---|---|---|---|
| GVWR (lb) | 18,000 | 6–13 of 13 | 16,480–18,000 |
| Dry weight (lb) | 15,222 | 11 of 13 | 12,881–15,644 |
| Cargo capacity (lb) | 2,778 | 5 of 13 | 2,095–3,970 |
| Dry hitch weight (lb) | 2,780 | 6 of 11 | 2,480–3,070 |
| Length | 43 ft 0 in | 13 of 13 | 35 ft 1 in–43 ft 0 in |
| Fresh tank (gal) | 70 | 1–12 of 13 | 70–77 |
| Grey tank (gal) | 137 | 13 of 13 | 88–137 |
| Black tank (gal) | 98 | 13 of 13 | 49–98 |
| Sleeps | 6 | 9–12 of 13 | 4–8 |
Either side of it by GVWR: Montana 3901RK matches it at 18,000 lb GVWR; Montana 3941FO matches it at 18,000 lb GVWR.
| Nearest Montana siblings | Length | Sleeps | Dry (lb) | GVWR (lb) | CCC (lb) | Hitch (lb) | Fresh (gal) |
|---|---|---|---|---|---|---|---|
| Montana 3915TB | 43 ft 0 in | 6 | 15,222 | 18,000 | 2,778 | 2,780 | 70 |
| Montana 3761FL | 41 ft 0 in | 6 | 14,951 | 18,000 | 3,049 | 2,880 | 70 |
| Montana 3941FO | 42 ft 7 in | 6 | 15,644 | 18,000 | 2,356 | 2,810 | 70 |
| Montana 3901RK | 42 ft 4 in | 4 | 14,755 | 18,000 | 3,245 | — | 70 |
| Montana 3795FK | 39 ft 11 in | 6 | 14,030 | 18,000 | 3,970 | 3,070 | 70 |
| Montana 3857BR | 40 ft 11 in | 8 | 15,618 | 18,000 | 2,382 | 3,050 | 70 |
All 13 Montana floorplans: Montana line hub.
| Other lines, nearest by GVWR | GVWR (lb) | Dry (lb) | Sleeps | Length |
|---|---|---|---|---|
| 3915TB | 18,000 | 15,222 | 6 | 43 ft 0 in |
| Cedar Creek 381MUD | 18,000 | 15,429 | 8 | 43 ft 5 in |
| Influence 3003RL | 18,000 | 12,500 | 4 | 34 ft 11 in |
| Paradigm 375RD | 18,000 | 14,771 | 5 | 41 ft 9 in |
| Puma Grand Mesa 395FKL | 18,000 | 14,929 | — | 42 ft 7 in |
| Bighorn 38RE | 17,995 | 15,275 | 4 | 42 ft 6 in |
| North Point 382FLRB | 17,995 | 15,470 | 8 | 43 ft 10 in |
Against the 3915TB: the Cedar Creek 381MUD sleeps 2 more; the Influence 3003RL is 8 ft shorter and sleeps 2 fewer; the Paradigm 375RD is 1 ft shorter and sleeps 1 fewer.
08 Common questions about the 3915TB
How much does the 3915TB weigh?
15,222 lb dry; 18,000 lb GVWR, the most it may weigh loaded.
How much can the 3915TB carry?
2,778 lb, 15% of its GVWR (median across 307 fifth wheels here: 19%). A full fresh tank uses 584 lb of it.
What is the pin weight of the 3915TB?
2,780 lb dry, 18% of the dry weight (median across 386 fifth wheels here: 19%).
What size tow vehicle does the 3915TB need?
A tow rating of at least 18,000 lb, plus payload for the loaded pin weight, passengers and cargo.
How many people does the 3915TB sleep?
It is rated to sleep 6. 1 of the 13 Montana floorplans that publish a count sleep more.
What are the tank capacities on the 3915TB?
Fresh 70, grey 137, black 98 gallons. Off hookups, fresh water runs out first.
How long is the 3915TB?
43' 0" overall, tongue or pin box included.
From the figures above.
09 What this page publishes, and what it does not
16 of the 18 fields this catalogue tracks are published for the 3915TB. Not published: tire specification, awning.
Sourcing rules: methodology.
10 Manuals & documents
Sources: keystonerv.com, library.rvusa.com (linked below); the full source note is at the foot of the page.
11 NHTSA safety record
NHTSA holds 34 recall campaigns and 154 owner complaints against the Montana line. They are counted separately: a recall is a confirmed defect with a remedy, a complaint one owner’s unverified account.
What to look at on a used one. Across the 154 complaints filed on this line the most-reported components are tires (32%), structure (17%) and equipment (16%).
Recall coverage here is not complete, and complaints are owners’ unverified reports (how this record is built). Check a specific VIN at NHTSA before you buy. Full tables are on the Montana line page.