Slippery roads — California Permit Test
Slippery roads on the California permit test — 8 rules, each with the reason behind it and a question on it while it is fresh.
The rules
On a wet road, reduce your speed by 5 to 10 mph.
Wet pavement takes a slice of your grip away, and the speed is how you pay it back.
Wet road: Reduce your speed by 5 to 10 mph.
On packed snow, reduce your speed by half.
Packed snow is polished by every car that goes over it, and it gets slicker as the day goes on.
Packed snow: Reduce your speed by half.
On ice, reduce your speed to no more than 5 mph.
On ice you have almost no grip at all, and 5 mph is a speed you can survive losing it at.
Ice: Reduce your speed to no more than 5 mph.
Shade from trees or buildings can hide icy spots on cold wet days, because those areas freeze first and dry out last.
The patch of road that never sees the sun is the patch that is still frozen at noon.
Shade from trees or buildings can hide icy spots on cold, wet days.
Bridges and overpasses tend to freeze before the rest of the road and can have icy spots.
A bridge has cold air underneath it as well as on top, so it loses its heat first.
Bridges and overpasses tend to freeze before the rest of the road.
When it starts to rain the pavement can be very slippery, especially if it has been dry and hot for some time, because oil and dust have not been washed away.
The first few minutes of rain lift the oil off the road before washing it away.
Slow down at the first sign of rain, drizzle, or snow on the road. This is especially true if it has been dry and hot for some time, because oil and dust on the road’s surface have not been washed away.
In a heavy rainstorm or snowstorm you may not be able to see more than 100 feet ahead, and if you cannot see farther than 100 feet it is not safe to drive faster than 30 mph.
A hundred feet at thirty miles an hour is about all the stopping room you have.
If you cannot see farther than 100 feet,
If you drive in snowy areas, carry snow chains for your tires, in the correct number and type for your vehicle.
Chains bite into packed snow the way a tire cannot, and the wrong size fits nothing.
If you drive in snowy areas, carry snow chains for your tires. Snow chains give your tires more traction.
On the test
By how much should you reduce your speed on a wet road?
5 to 10 mph. Wet pavement takes a slice of your grip away, and the speed is how you pay it back. California Driver’s Handbook, p.61: “Wet road: Reduce your speed by 5 to 10 mph.”
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 California Driver’s Handbook, published by the California Department of Motor Vehicles, and against the state code itself. Last checked 2026-09-21.
- src/assets/drivers-manuals/CA.pdf (California Driver’s Handbook, DL 600 ENGLISH (REV. 6/2025), retrieved 2026-09-14; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/CA.pages.txt (the pdftotext -layout fixture every citation here was cut against and verified against; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/SOURCES.json, CA entry — the folio offset of 6 and its basis, the three non-law pages, the two sign gallery pages, and the record of why California’s exam shape is this app’s own
- docs/plans/chosen-exam-shapes.md section 5 — the decision that a state publishing neither exam figure ships 40/32 with both disclosed
- docs/plans/how-to-build-laws.md — the rule that the handbook is the syllabus and nothing enters this file without a page in it