01 What makes it unique
Vanleigh RV lists the 2023 Ambition 399THX at 17,130 lb dry, a GVWR of 21,000 lb, a net carrying capacity of 3,870 lb and a hitch weight of 4,260 lb. Its dry weight plus its carrying capacity comes to exactly its GVWR.
It is 45'7" long. Vanleigh RV prints no tank capacity for it.
Among the 2 Ambition floorplans Vanleigh RV’s 2023 Ambition brochure lists with a published dry weight, it is number 2 from the lightest, in a range from 16,900 lb (Ambition 399TH) to 17,130 lb (Ambition 399THX). Every figure in that comparison is Vanleigh RV’s, for the same model year.
Every number on this page was read on 6 Nov 2026 from Vanleigh RV’s 2023 Ambition brochure, the maker’s own dated document for model year 2023.
How the 399THX differs from the other Ambition floorplan. How these ranks are worked out.
Next to the 399TH, the nearest lighter floorplan by dry weight, the 399THX is 230 lb heavier by dry weight, has 230 lb less cargo capacity and is 2 ft longer; the two publish the same GVWR.
02 Full specifications
Dimensions
- Exterior length
- 45'7"
- Exterior height
- Not published by Vanleigh RV
- Exterior width
- Not published by Vanleigh RV
- Interior height
- Not published by Vanleigh RV
Weights
- Dry / unit base weight (UVW)
- 17,130 lb
- GVWR (max loaded)
- 21,000 lb
- Net cargo / payload (CCC)
- 3,870 lb
- Hitch weight
- 4,260 lb
Capacities
- Fresh water
- Not published by Vanleigh RV
- Grey water
- Not published by Vanleigh RV
- Black water
- Not published by Vanleigh RV
Running gear
- Hitch type
- Not stated per floorplan by Vanleigh RV
- Tire size
- Not published by Vanleigh RV
Sleeping & layout
- Sleeps
- Not published by Vanleigh RV
- Model year (as printed)
- page 1: "MODEL YEAR 2023" with "Initial MY2023 Model Change Plans, Subject to Change in Full Production Date Revised: 11/4/22"
- Plan pairing
- page 5: floorplan headed "399THX" with its spec block beside it (checked on the rendered page)
- Weight basis (as printed)
- "All weights are unloaded and based off an average. All lengths are from pinbox to rear bumper."
- Garage (as printed)
- "13' GARAGE" / "15' GARAGE" labels on the floorplans; "Option for 15' Garage (399THX)"
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
Weight budget
Axles, wheels and nose shape are schematic; not a floorplan. Data: dataset.
03 The Ambition floorplan family
Vanleigh RV’s 2023 Ambition brochure lists 2 Ambition floorplans; every one with a printed weight has a page here.
| Floorplan | Nominal | Sleeps | Notable |
|---|---|---|---|
| Ambition 399TH | 43'7" | — | Profiled |
| Ambition 399THX | 45'7" | — | Profiled |
Vanleigh RV’s 2023 Ambition brochure lists 2 Ambition floorplans. Every one with a printed weight has a page here.
04 Notes on this floorplan
What Vanleigh RV does not publish for the Ambition 399THX
Vanleigh RV prints no tire size, interior height, grey-tank, black-tank, 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
16,900 lb dry and 21,000 lb GVWR, against this model’s 17,130 lb and 21,000 lb.
06 Loading it for a trip
Cargo capacity on the Ambition 399THX is 3,870 lb.
No source publishes a tongue weight for the Ambition 399THX, so its hitch load has to come from a scale ticket taken with the trailer hitched.
07 Where this floorplan sits
Closest sibling: the Ambition 399TH, nearest on the published figures. It differs on 3 of the 4 fields both publish (this plan first): length 45 ft 7 in vs 43 ft 7 in; dry weight 17,130 lb vs 16,900 lb; cargo capacity 3,870 lb vs 4,100 lb. They match on GVWR.
Either side of it by GVWR: Ambition 399TH matches it at 21,000 lb GVWR.
| Nearest Ambition siblings | Length | Sleeps | Dry (lb) | GVWR (lb) | CCC (lb) | Hitch (lb) | Fresh (gal) |
|---|---|---|---|---|---|---|---|
| Ambition 399THX | 45 ft 7 in | — | 17,130 | 21,000 | 3,870 | — | — |
| Ambition 399TH | 43 ft 7 in | — | 16,900 | 21,000 | 4,100 | — | — |
All 2 Ambition floorplans: Ambition line hub.
| Other lines, nearest by GVWR | GVWR (lb) | Dry (lb) | Sleeps | Length |
|---|---|---|---|---|
| Ambition 399THX | 21,000 | 17,130 | — | 45 ft 7 in |
| Sportster X 3914X | 20,000 | 14,620 | 9 | 44 ft 5 in |
| Venom Robby Gordon Speed UTV Edition 3815RG | 19,000 | 13,420 | — | 42 ft 10 in |
| Beacon 41FLB | 18,500 | 16,360 | — | 42 ft 6 in |
| Vilano 377FL | 18,500 | 15,600 | — | 42 ft 6 in |
| Highlander HF383H | 18,000 | 12,400 | — | 42 ft 4 in |
| New Vision Sportster 38P | 18,000 | 13,650 | — | 40 ft 5 in |
Against the Ambition 399THX: the Sportster X 3914X is 1,000 lb lighter and 1 ft shorter; the Venom Robby Gordon Speed UTV Edition 3815RG is 2,000 lb lighter and 3 ft shorter; the Beacon 41FLB is 2,500 lb lighter and 3 ft shorter.
08 Common questions about the Ambition 399THX
How much does the Ambition 399THX weigh?
17,130 lb dry; 21,000 lb GVWR, the most it may weigh loaded.
How much can the Ambition 399THX carry?
3,870 lb, 18% of its GVWR (median across 1,416 travel trailers here: 23%).
What size tow vehicle does the Ambition 399THX need?
A tow rating of at least 21,000 lb, plus payload for the loaded tongue weight, passengers and cargo.
How long is the Ambition 399THX?
45'7" overall, tongue or pin box included.
From the figures above.
09 What this page publishes, and what it does not
4 of the 18 fields this catalogue tracks are published for the Ambition 399THX. Not published: hitch weight, exterior height, exterior width, interior height, fresh tank, grey tank, black tank, sleeps, slide count, axle count, tire specification, awning, refrigerator, air conditioning.
Sourcing rules: methodology.
10 Manuals & documents
Sources: library.rvusa.com (linked below); the full source note is at the foot of the page.
11 NHTSA safety record
NHTSA holds 1 recall campaign against the Ambition line (a recall and a complaint are not the same thing).
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 Ambition line page.