Tire tread penny test — South Dakota Permit Test
Tire tread penny test on the South Dakota permit test — 1 rule, each with the reason behind it and a question on it while it is fresh.
The rules
To check tread depth, place a penny with Lincoln headfirst into the deepest-looking groove; if you can see all of his head, the tires are too worn and must be replaced.
Bald tires cannot push water away, so the car slides on a wet road and will not stop.
If yes, your tires are too worn—do not drive on them, and make sure to get them replaced.
On the test
In the penny test, what tells you a tire is too worn to drive on?
You can see all of Lincoln’s head. Bald tires cannot push water away, so the car slides on a wet road and will not stop. South Dakota Driver License Manual, p.23: “If yes, your tires are too worn—do not drive on them, and make sure to get them replaced.”
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.
All South Dakota permit topics
Where these come from
Every rule here is checked against South Dakota Driver License Manual, published by the South Dakota Department of Public Safety, and against the state code itself. Last checked 2026-10-04.
- src/assets/drivers-manuals/SD.pdf (South Dakota Driver License Manual, Revised 11/2024, South Dakota Department of Public Safety, retrieved 2026-09-14 and re-checked 2026-10-04; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/SD.pages.txt (pdftotext -layout, the fixture every citation here was cut from and verified against; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/SD-exam.html (South Dakota Department of Public Safety, South Dakota Driver License Testing Information, KB0043731, read 2026-10-04; states the 80% rate; sha256 pinned under examSource)
- https://www.sd.gov/dps?id=cs_kb_article_view&sysparm_article=KB0043733 (read 2026-10-04; links the manual)