01 What makes it unique
Forest River lists the 2020 XLR Thunderbolt 381AMP at 15,449 lb dry, a net carrying capacity of 5,551 lb and a pin weight of 3,335 lb. It prints no GVWR for it.
It is 44' 0" long and 13' 4" high. Forest River prints its tanks as 102 gal fresh, 100 gal grey, 80 gal black.
Among the 5 XLR Thunderbolt floorplans Forest River’s XLR Thunderbolt brochure (filed in Forest River’s /brochures/2020/ folder; the brochure prints no year) lists with a published dry weight, it is number 2 from the lightest, in a range from 13,644 lb (XLR Thunderbolt 369AMP) to 16,364 lb (XLR Thunderbolt 422AMP). Every figure in that comparison is Forest River’s, for the same model year.
Every number on this page was read on 6 Nov 2026 from Forest River’s XLR Thunderbolt brochure (filed in Forest River’s /brochures/2020/ folder; the brochure prints no year); model year 2020 comes from where the maker files it on its own site, not from the document’s text.
How the 381AMP differs from the other four XLR Thunderbolt floorplans. Most distinctive first. How these ranks are worked out.
- Cargo capacity, 5,551 lb: largest of five; next is the 382AMP (5,271 lb).
- Fresh tank, 102 gal: smallest of five; next is the 369AMP (150 gal).
- Dry weight, 15,449 lb: second-lightest of five, between the 369AMP (13,644 lb) and the 382AMP (15,729 lb).
- Pin weight as a share of dry weight, 21.6%: second-smallest of five, between the 413AMP (20.4%) and the 422AMP (22.3%).
- Grey tank, 100 gal: second-largest of five, between the 422AMP (86 gal) and the 413AMP (118 gal).
- Pin weight, 3,335 lb: third-lightest of five, between the 413AMP (3,323 lb) and the 422AMP (3,643 lb).
- Length, 44 ft: third-shortest of five, between the 382AMP (43 ft 9 in) and the 413AMP and 422AMP (44 ft 6 in).
- Black tank, 80 gal: shared with the 382AMP; of five, one smaller and two larger, nearest the 369AMP (32 gal) and the 413AMP and 422AMP (86 gal).
Next to the 369AMP, the nearest lighter floorplan by dry weight, the 381AMP is 1,805 lb heavier by dry weight, has 2,055 lb more cargo capacity, has a pin weight 195 lb heavier, is 4 ft 2 in longer, has a fresh tank 48 gal smaller, has a grey tank 36 gal larger and has a black tank 48 gal larger; the two publish the same exterior height.
Next to the 382AMP, the nearest heavier floorplan by dry weight, the 381AMP is 280 lb lighter by dry weight, has 280 lb more cargo capacity, has a pin weight 425 lb lighter, is 3 in longer, has a fresh tank 56 gal smaller and has a grey tank 20 gal larger; the two publish the same exterior height and black tank.
02 Full specifications
Dimensions
- Exterior length
- 44' 0"
- Exterior height
- 13' 4"
- Exterior width
- 102"
- Interior height
- Not published by Forest River
Weights
- Dry / unit base weight (UVW)
- 15,449 lb
- GVWR (max loaded)
- Not published by Forest River
- Net cargo / payload (CCC)
- 5,551 lb
- Hitch / pin weight
- 3,335 lb
Capacities
- Fresh water
- 102 gal
- Grey water
- 100 gal
- Black water
- 80 gal
Running gear
- Hitch type
- Fifth wheel (pin box)
- Tire size
- Not published by Forest River
Sleeping & layout
- Sleeps
- Not published by Forest River
- Model year source
- The brochure prints no model year; the maker files it in its own /brochures/2020/ folder.
- Tires (as printed)
- Standards list: "16” Radial Tires w/ Nitrofill™"
- Awning
- 20'
How these published figures sit against the rest of the catalogue: travel trailer tongue weight by size; fresh, grey and black tank sizes; camper trailer size chart.
Drawn to scale
Size, with end view
Holding tanks
Axles, wheels and nose shape are schematic; not a floorplan. Data: dataset.
03 The XLR Thunderbolt floorplan family
Forest River’s XLR Thunderbolt brochure (filed in Forest River’s /brochures/2020/ folder; the brochure prints no year) lists 5 XLR Thunderbolt floorplans; every one with a printed weight has a page here.
| Floorplan | Nominal | Sleeps | Notable |
|---|---|---|---|
| XLR Thunderbolt 369AMP | 39' 10" | — | Profiled |
| XLR Thunderbolt 381AMP | 44' 0" | — | Profiled |
| XLR Thunderbolt 382AMP | 43' 9" | — | Profiled |
| XLR Thunderbolt 413AMP | 44' 6" | — | Profiled |
| XLR Thunderbolt 422AMP | 44' 6" | — | Profiled |
Forest River’s XLR Thunderbolt brochure (filed in Forest River’s /brochures/2020/ folder; the brochure prints no year) lists 5 XLR Thunderbolt floorplans. Every one with a printed weight has a page here.
04 Notes on this floorplan
What Forest River does not publish for the XLR Thunderbolt 381AMP
Forest River prints no GVWR, tire size, interior height, sleeping capacity for this model, so none is given. Nothing is filled from a sibling model, a different model year or a dealer listing.
Read the label on the trailer
Federal rules put a load-carrying label inside every RV trailer: its unloaded weight with full propane, its cargo carrying capacity and its GVWR (49 CFR 571.110 and 571.120). Those figures come from the trailer itself and govern the towing decision.
05 How it compares
13,644 lb dry and Not published by Forest River GVWR, against this model’s 15,449 lb and Not published by Forest River.
15,729 lb dry and Not published by Forest River GVWR, against this model’s 15,449 lb and Not published by Forest River.
06 Loading it for a trip
A full 102-gallon fresh tank is about 847 lb of water, 15% of the XLR Thunderbolt 381AMP’s 5,551 lb cargo capacity, leaving 4,704 lb. Across 5 XLR Thunderbolt floorplans the water share runs 15% to 36%, and this plan’s is the lowest. Nearest on that share: XLR Thunderbolt 382AMP at 25%.
07 Where this floorplan sits
Closest sibling: the XLR Thunderbolt 382AMP, nearest on the published figures. It differs on 6 of the 7 fields both publish (this plan first): length 44 ft 0 in vs 43 ft 9 in; dry weight 15,449 lb vs 15,729 lb; cargo capacity 5,551 lb vs 5,271 lb; hitch weight 3,335 lb vs 3,760 lb; fresh tank 102 gal vs 158 gal; grey tank 100 gal vs 80 gal. They match on black tank.
| XLR Thunderbolt plans | This plan | Position, low to high | Range |
|---|---|---|---|
| Dry weight (lb) | 15,449 | 2 of 5 | 13,644–16,364 |
| Cargo capacity (lb) | 5,551 | 5 of 5 | 3,496–5,551 |
| Hitch weight (lb) | 3,335 | 3 of 5 | 3,140–3,760 |
| Length | 44 ft 0 in | 3 of 5 | 39 ft 10 in–44 ft 6 in |
| Fresh tank (gal) | 102 | 1 of 5 | 102–158 |
| Grey tank (gal) | 100 | 4 of 5 | 64–118 |
| Black tank (gal) | 80 | 2–3 of 5 | 32–86 |
Either side of it by dry weight: XLR Thunderbolt 369AMP is 1,805 lb lighter (13,644 lb dry); XLR Thunderbolt 382AMP is 280 lb heavier (15,729 lb dry).
| Nearest XLR Thunderbolt siblings | Length | Sleeps | Dry (lb) | GVWR (lb) | CCC (lb) | Hitch (lb) | Fresh (gal) |
|---|---|---|---|---|---|---|---|
| XLR Thunderbolt 381AMP | 44 ft 0 in | — | 15,449 | — | 5,551 | 3,335 | 102 |
| XLR Thunderbolt 382AMP | 43 ft 9 in | — | 15,729 | — | 5,271 | 3,760 | 158 |
| XLR Thunderbolt 413AMP | 44 ft 6 in | — | 16,280 | — | 4,720 | 3,323 | 158 |
| XLR Thunderbolt 422AMP | 44 ft 6 in | — | 16,364 | — | 4,636 | 3,643 | 158 |
| XLR Thunderbolt 369AMP | 39 ft 10 in | — | 13,644 | — | 3,496 | 3,140 | 150 |
All 5 XLR Thunderbolt floorplans: XLR Thunderbolt line hub.
| Other lines, nearest by dry weight | GVWR (lb) | Dry (lb) | Sleeps | Length |
|---|---|---|---|---|
| XLR Thunderbolt 381AMP | — | 15,449 | — | 44 ft 0 in |
| Beacon 42RKB | 18,500 | 15,400 | — | 42 ft 6 in |
| Vilano 385RD | 18,500 | 15,500 | — | 42 ft 6 in |
| Sportster X 3914X | 20,000 | 14,620 | 9 | 44 ft 5 in |
| Salem Villa 42ZEN | — | 14,404 | — | 44 ft 11 in |
| Mobile Suites 36 RSSB3 | — | 16,600 | — | 38 ft 7 in |
| New Vision Sportster 41KG | 18,000 | 14,265 | — | 43 ft 5 in |
Against the XLR Thunderbolt 381AMP: the Beacon 42RKB is 49 lb lighter and 2 ft shorter; the Vilano 385RD is 51 lb heavier and 2 ft shorter; the Sportster X 3914X is 829 lb lighter.
08 Common questions about the XLR Thunderbolt 381AMP
How much can the XLR Thunderbolt 381AMP carry?
5,551 lb. A full fresh tank uses 847 lb of it.
What is the pin weight of the XLR Thunderbolt 381AMP?
3,335 lb as published, 22% of the dry weight (median across 2,002 travel trailers here: 12%).
What are the tank capacities on the XLR Thunderbolt 381AMP?
Fresh 102, grey 100, black 80 gallons. Off hookups, fresh water runs out first.
How long is the XLR Thunderbolt 381AMP?
44' 0" overall, tongue or pin box included.
From the figures above.
09 What this page publishes, and what it does not
10 of the 18 fields this catalogue tracks are published for the XLR Thunderbolt 381AMP. Not published: GVWR, interior height, sleeps, slide count, axle count, tire specification, refrigerator, air conditioning.
Sourcing rules: methodology.
10 Manuals & documents
Sources: forestriverinc.com (linked below); the full source note is at the foot of the page.