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
Verified specs, drawn to scale
Original graphics built from this floorplan’s own verified figures.
Loaded weight budget
Size, drawn to scale
Holding tanks
These graphics are generated from the same verified record that builds the table above, and are published under this site’s own licence — nothing here is traced from, or derived from, a manufacturer drawing or photo. Where a figure is not published for this plan, the graphic that would need it is omitted rather than estimated. The full record is in the published dataset.
What it takes to tow this
Built from this floorplan’s verified weights. We publish the trailer side only.
We do not publish tow ratings for specific trucks. A single model can vary by thousands of pounds depending on engine, axle ratio, cab, drivetrain and package — the only authoritative figure is the one on your own door jamb. Loaded pin percentages are industry convention for fifth wheels (15–25% of loaded weight), not a measurement of this unit. Hitch classes are not used here as a rating: SAE J684 covers trailers to 10,000 lb GVWR and does not define Class V, and capacity boundaries differ between manufacturers — read the rating stamped on your hitch. On this plan the convention band’s low end fell below the published dry figure, so the range starts at the published dry weight instead — loaded is never lighter than dry.
03 The Montana floorplan family
Montana is Keystone's flagship luxury fifth wheel and the best-selling luxury fifth wheel in North America. 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 | Best-selling 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 the best-selling luxury fifth wheel in North America and Keystone's flagship towable. 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 fp-slug and title checked; 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 What owners & reviewers report
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
This floorplan carries its water comfortably. A full 70-gallon fresh tank is roughly 21% of the 2,778-pound cargo capacity, leaving the 3915TB with a usable gear budget even when you tow full.
| Weight budget | Figure | What it means |
|---|---|---|
| Cargo capacity as published (CCC) | 2,778 lb | Everything you add: gear, water, propane, batteries, food, people’s belongings. |
| Fresh tank filled (70 gal × 8.34 lb) | −584 lb | Water is the heaviest thing most owners add, and it is added first. |
| Cargo budget left with a full fresh tank | 2,194 lb | 21% of this plan’s capacity is spent before a single bag is loaded. |
| Per sleeping position, water aboard | 366 lb | A rough share of what is left across the 6 berths this plan sleeps. |
The published dry pin weight of 2,780 pounds is 18% of this floorplan’s 15,222-pound dry weight. Fifth-wheel pin weight rides in the bed of the truck, so it comes off payload rather than off tow rating — and it rises with the trailer as you load it, not in proportion to what you put over the axles.
Nothing above changes the ceiling. Loaded to its 18,000-pound GVWR the 3915TB is towing 2,778 pounds more than its 15,222-pound dry figure, and that is the number your vehicle has to be rated for — not the brochure weight.
Tank balance is generous here: 70 gallons of fresh against 137 grey and 98 black, so waste capacity keeps pace with supply and the fresh tank is the constraint that ends a dry stay.
07 Where this floorplan sits
Ranked by GVWR, the 3915TB sits 12 of 13 in the Montana line: 18,000 pounds against a line that runs from 16,480 to 18,000 pounds. That position is the useful thing to know, because the plans immediately either side of it are the real alternatives.
Either side of it in the same line: Montana 3901RK matches it exactly at 18,000 lb GVWR; and Montana 3941FO matches it exactly at 18,000 lb GVWR.
7 other Montana plans share this floorplan’s 18,000 lb GVWR, so the ranking above separates plans that tow to the same ceiling. On a shared chassis the figure that actually differs between them is cargo capacity and where the weight sits, not the rating.
| Comparable fifth wheels | 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. Those are differences in the published numbers only — what they cost, how they are built and how they live are separate questions each of those pages answers on its own terms.
Those are the nearest fifth wheels from other lines by weight — one per line, picked by proximity on that figure and nothing else. They are listed so the same tow vehicle can be checked against real alternatives, not because they are equivalent inside; layout, build and price diverge sharply across that group.
For scale, the Montana floorplans profiled here run 12,881 to 15,644 pounds dry and 35 to 43 feet of exterior length across 13 plans. Where a floorplan falls in that spread usually says more about which vehicle can tow it, and which site it fits, than the layout name does.
Every profiled floorplan in this line, with the full weight table, is on the Montana line hub.
08 Common questions about the 3915TB
How much does the 3915TB weigh?
It leaves the factory at 15,222 pounds dry, and its manufacturer-set loaded ceiling (GVWR) is 18,000 pounds. Real towing weight lands between the two and depends entirely on what you load. Use the GVWR when matching a tow vehicle; the dry figure is only useful for comparing floorplans against each other.
How much can the 3915TB carry?
Cargo carrying capacity is 2,778 pounds. That is the whole budget: water, propane, batteries, gear and everything you bring. Filling the 70-gallon fresh tank uses about 584 pounds of that.
What is the pin weight of the 3915TB?
The published dry pin weight is 2,780 pounds. It is measured empty; loaded, it runs higher, and it comes out of your tow vehicle’s payload rather than its tow rating.
What size tow vehicle does the 3915TB need?
Your vehicle needs a tow rating of at least 18,000 pounds — this floorplan’s GVWR — and enough payload left over for the hitch load, passengers and anything in the bed. This site does not publish tow ratings for specific vehicles, because one truck model varies by thousands of pounds across engine, axle ratio, cab and package. The figure that governs is the payload sticker on your own door jamb.
How many people does the 3915TB sleep?
It is rated to sleep 6. Rated sleeping positions include convertible furniture, so count the beds against how you actually travel rather than against the number.
What are the tank capacities on the 3915TB?
Fresh 70 gallons, grey 137 gallons, black 98 gallons. Tank sizes set how long the floorplan can sit away from hookups, and the smallest of the three is what ends the stay.
How long is the 3915TB?
Exterior length is 43' 0". Measure against your site length and your storage before committing — the exterior figure is the one that has to fit, and it includes the tongue or pin box.
Every figure in these answers is read from this page’s verified specification table. Where the manufacturer publishes nothing, the question is not answered rather than estimated.
09 What this page publishes, and what it does not
This catalog tracks 18 specification fields per floorplan. Named sources publish 16 of them for the 3915TB. The rest are not shown, because the alternative is reading a figure across from a sibling floorplan or from what the segment usually does — and a number nobody published is worth less than an admitted gap.
Not published for this floorplan: tire specification, awning. If you find one of these in a manufacturer document for this plan, it belongs on this page.
The completeness figure at the foot of this page (99%) measures the same thing on the full field set: it is a measurement of how much this floorplan’s manufacturer publishes, not of how much research went into the page.
How every figure here was sourced and checked is set out on the methodology page.
11 NHTSA safety record
This floorplan belongs to the Montana line, and NHTSA holds 34 recall campaigns and 154 owner complaints against that line. They are separate records and are not added together — a recall is a manufacturer-confirmed defect with a remedy; a complaint is one owner’s account, which NHTSA does not verify.
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%). That is where owners of this family have had trouble, so it is where an inspection is worth the time.
Recall coverage is not complete — our harvest of NHTSA’s recall API ran 1,556 queries, of which 0 failed and 242 returned an explicit zero. A line can still be under-reported where NHTSA files a roster under a parent name, or where a match rests on the wording of the recall rather than its model field. Complaints come from the complete bulk file but are unverified and self-selected: a high count tracks how many units a line sold at least as much as how well it was built. Check a specific VIN at NHTSA before you buy. Full tables are on the Montana line page.