Three second rule — Montana Permit Test
Three second rule on the Montana permit test — 4 rules, each with the reason behind it and a question on it while it is fresh.
The rules
Rear-end crashes, caused by following too closely, are very common; the "Three-Second Rule" tells you if you are following too closely.
A driver tucked in close behind cannot stop when the car ahead stops suddenly.
It is called the “Three-Second Rule,” and it works at any speed.
The three-second rule works at any speed.
A driver who keeps a fixed number of car lengths has far too little room at highway speed.
It is called the “Three-Second Rule,” and it works at any speed.
To use the three-second rule, watch for the rear of the vehicle ahead to pass a stationary point and count the seconds it takes you to reach the same spot.
Guessing the gap by eye fools most drivers into following too closely.
Watch for when the rear of the vehicle ahead passes a sign, pole, or any other stationary point.
If you pass the mark before you finish counting, you are following too closely: drop back and count again at another spot.
A driver who checks once and never again drifts back up close behind the car ahead.
You are following too closely if you pass the mark before you finish counting.
On the test
How many seconds behind the vehicle ahead does the manual's basic following rule call for?
3 seconds. A driver tucked in close behind cannot stop when the car ahead stops suddenly. Montana Driver Manual, p.64: “It is called the “Three-Second Rule,” and it works at any speed.”
How this works
Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.
You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.
Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.
What it costs
- One payment, once — not a subscription. Nothing renews and there is nothing to cancel, for an exam you sit one time.
- Free to start: a 10-question test and the first section of cards. No sign-up and no account.
- Paying opens the rest of the cards, unlimited full-length practice tests, and retests built from exactly the questions you got wrong.
- Every level up to Prepared — 3 tests passed in a row.
- Do the work, fail the real exam, and we refund you.
Where these come from
Every rule here is checked against Montana Driver Manual, published by the Montana Department of Justice, and against the state code itself. Last checked 2026-10-04.
- src/assets/drivers-manuals/MT.pdf (Montana Driver Manual, Revised April 2024, Montana Department of Justice, Motor Vehicle Division, retrieved 2026-09-14 and re-checked 2026-10-04; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/MT.pages.txt (scripts/mt-text.sh: pdftotext -layout except printed pp.24-26, which are plain; the fixture every citation here was cut from and verified against; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/MT-exam.html (Administrative Rules of Montana 23.3.121, Road Signs and Road Rules, as reproduced by the Legal Information Institute, read 2026-10-04; states the seven-miss pass mark; sha256 pinned under examSource)
- https://mvdmt.gov/forms-driver-license/ (read 2026-10-04; links the manual)