Idaho gives you 40 questions and lets you miss six. At 85% it is the highest passing bar of any state we cover, so a number you half remember is a number you get wrong. This page collects every figure worth committing to memory.
Speed limits
Idaho Code section 49-654 sets these. A posted sign always overrides the statutory figure.
| Where | Limit |
|---|---|
| Rural interstates (I-84, I-15, I-86) | 80 mph |
| Urban interstates | 65 mph |
| Trucks and vehicles towing on interstates | 70 mph |
| State highways | 65 to 70 mph |
| Other locations, unposted | 55 mph |
| Residential and business districts | 25 mph |
| School zones | 20 mph |
Alcohol limits
| Driver | Illegal at |
|---|---|
| Age 21 and over | 0.08% BAC |
| Under 21 | 0.02% BAC |
| Commercial license holders | 0.04% BAC |
| Excessive DUI, with mandatory jail | 0.20% BAC |
Idaho treats 0.20% as an aggravated category carrying a mandatory minimum jail term rather than a discretionary one. Refusing a chemical test after a lawful arrest triggers a license suspension under implied consent, separate from any conviction.
Permits and licenses
- Supervised Instruction Permit from 14 and a half. One of the earliest starts in the country.
- Driver education required under 17. At 17 or older it is not, and the permit becomes optional.
- Permit valid one year. If it expires before you are licensed, you sit the knowledge test again.
- Hold the permit six months if you are under 18 before the skills test.
- 50 hours supervised driving including 10 at night.
- Under 18 also needs a parent or guardian signature and proof of high school attendance or graduation.
- Teen licenses expire five days after the eighteenth birthday. Deliberately, to force a return visit.
Other numbers worth knowing
- Accident reporting: you must report a crash involving injury, death, or property damage over $1,500.
- Seat belts: required for all occupants, enforced as a secondary offense. Children under seven need an approved restraint.
- Following distance: three seconds minimum, four or more on snow, gravel, or behind a large vehicle.
- Fire hydrant: no parking within 15 feet.
- School buses: on an undivided road, traffic in both directions must stop for flashing red lights.
Open range, which is genuinely different
In designated open range areas, livestock are legally entitled to be on the roadway and are not fenced out. An OPEN RANGE sign is a real warning. If you hit an animal, the liability picture differs from a state where livestock must be fenced in.
Practically: slow down, stop if animals are on the road, and wait. Cattle scatter unpredictably and often move toward a vehicle rather than away from it.
Mountain driving
- Long descents: lower gear, not continuous braking. Brakes overheat and fade.
- Narrow mountain roads: the downhill vehicle yields, since an uphill vehicle struggles to stop and restart.
- Runaway truck ramps are for vehicles with failed brakes. Never park in one.
- Chain requirements on passes are enforceable, fitted at the chain-up area rather than in a lane.
- Elk and moose are tall enough that the body comes through the windshield rather than over the hood.
- Black ice forms first on bridges, overpasses and shaded curves.
Signs and right of way
Shapes: octagon is stop. Upside-down triangle is yield. Diamond warns. Pentagon means school. Round means a railroad crossing ahead, a crossbuck means you are at it. A pennant on the left marks a no passing zone.
Colors: red prohibits, yellow warns about the road, orange means workers, fluorescent yellow-green means people crossing, green guides, blue means services, brown means parks, white with black lettering is law.
Right of way: yield to the right at uncontrolled intersections and four-way stops taken together. Yield to oncoming traffic when turning left on a plain green. Yield to pedestrians in marked crosswalks. Pull right and stop for emergency vehicles, never in an intersection. Move over a lane for stopped emergency vehicles, or slow right down if you cannot.
Use this properly
At 85% there is no room for guessing, so a cheat sheet is the last read-through rather than the study plan. The Idaho Driver’s Handbook is the source of every exam question and it is free. Read it, use this page to check the numbers stuck, then take the full practice test until you are consistently above 90%. For documents and the whole process, see the Idaho permit guide.
Disclaimer: Pass The Permit is an independent study resource and is not affiliated with, endorsed by, or connected to the Idaho Transportation Department or any government agency. Laws change and local ordinances vary. Always confirm current figures against the official Idaho Driver’s Handbook and Idaho Code Title 49 before relying on them.