Verified
Montana Trailer Brake Laws 2026: Required Over 3,000 lb
Montana requires brakes on all wheels except for trailers, semitrailers, and pole trailers not exceeding 3,000 lb gross weight when the trailer wheel weight is no more than 40% of the towing vehicle gross weight and the combination meets performance requirements.
- Brake threshold
- 3,000lbgross weight
- Breakaway switch
- Required
- Safety chains
- Required
- Towing speed
- Posted limits
- Double towing
- Not recorded
On this page8 sections
Quick answer: 3,000 lb gross weight
In Montana, trailer brakes are currently listed at 3,000 lb (gross weight). Montana measures gross weight, so weigh the trailer as you actually tow it.
Montana trailer equipment rules
Breakaway switch
Every trailer with air- or vacuum-actuated brakes, and every one over 3,000 lb gross weight manufactured or assembled after January 1 1966, must have brakes on all wheels that apply automatically and promptly and remain applied at least 15 minutes upon breakaway.
- Applies when
- Trailer type and weight may matter
- Source
- Mont. Code Ann. 61-9-305
- Last checked
- 2026-08-21
Safety chains
Only a trailer, semitrailer or pole trailer weighing 3,000 lb or less must carry a steel safety chain or cable of at least one-quarter-inch diameter on the front, fastened to the towing unit's hitch or frame member — not the ball — so the drawbar cannot drop. Heavier trailers fall under the brake sections instead.
- Applies when
- Conventional trailer couplings
- Last checked
- 2026-08-21
Speed / lane rule
No towing-specific speed limit; follow posted limits. A separate section caps trucks and truck-tractors over one-ton rated capacity and permitted multi-trailer combinations, not trailer towing generally.
- Applies when
- Posted roads and vehicle combinations
- Source
- Mont. Code Ann. 61-8-303
- Last checked
- 2026-08-21
Double towing
Needs verification with Montana Code Annotated.
- Applies when
- Multiple-trailer combinations
- Source
- Verified
- Last checked
- 2026-07-13
Read against the linked sources on . Statutes change and enforcement varies by trailer type — confirm before you tow.
Check your setup
How the 3,000 lb threshold applies to three trailers
Montana measures gross weight, so the weight of the trailer as loaded is what counts.
| Example trailer | Weight checked | Against 3,000 lb |
|---|---|---|
| Small utility trailer | 1,650 lb | Under the Montana threshold by 1,350 lb |
| Loaded just under the line | 2,900 lb | Inside the Montana limit, but one heavy load away from crossing it |
| Mid-size travel trailer | 4,800 lb | Over the Montana threshold by 1,800 lb — brakes required |
How Montana compares with neighbouring states
1 of the 4 states bordering Montana set a stricter brake threshold, so a trailer that is legal here may need brakes as soon as you cross the line. Equip for the strictest state on your route.
| Bordering state | Brake threshold | Compared with Montana |
|---|---|---|
| Idaho | 1,500 lb unladen weight | 1,500 lb stricter |
| North Dakota | verified trailer-type rule | Different rule type — compare directly |
| South Dakota | 3,000 lb gross weight | Same threshold |
| Wyoming | verified stopping-distance performance rule | Different rule type — compare directly |
Planning a multi-state trip? The route brake law checker compares every state on a route at once.
Official source links
Montana towing law FAQ
Are trailer brakes required in Montana?
Montana currently lists a trailer brake threshold at 3,000 lb gross weight. Always verify the official state source before towing.
What weight requires trailer brakes in Montana?
The current data lists 3,000 lb gross weight as the brake threshold.
Is a breakaway switch required in Montana?
Every trailer with air- or vacuum-actuated brakes, and every one over 3,000 lb gross weight manufactured or assembled after January 1 1966, must have brakes on all wheels that apply automatically and promptly and remain applied at least 15 minutes upon breakaway. (Mont. Code Ann. 61-9-305)
Are safety chains required in Montana?
Only a trailer, semitrailer or pole trailer weighing 3,000 lb or less must carry a steel safety chain or cable of at least one-quarter-inch diameter on the front, fastened to the towing unit's hitch or frame member — not the ball — so the drawbar cannot drop. Heavier trailers fall under the brake sections instead. (Mont. Code Ann. 61-9-208(6)(a))
Can I tow two trailers in Montana?
Needs verification with Montana Code Annotated.
Is there a towing speed limit in Montana?
No towing-specific speed limit; follow posted limits. A separate section caps trucks and truck-tractors over one-ton rated capacity and permitted multi-trailer combinations, not trailer towing generally. (Mont. Code Ann. 61-8-303)
Does Montana measure trailer weight as GVWR or actual weight?
Montana uses gross weight, so weigh the trailer as you actually tow it rather than reading the data plate.
Where can I verify Montana towing laws?
Start with the 3 official sources linked on this page, beginning with MCA 61-9-304 brakes required on all wheels. Prefer state DOT, DMV, legislature, or public-safety pages over summaries from private websites. This page was last checked on 2026-07-13.
Disclaimer: educational summary, not legal advice. Statutes and enforcement practice change — verify the Montana sources linked above before towing.