Tire maintenance — Kentucky Permit Test
Tire maintenance on the Kentucky permit test — 6 rules, each with the reason behind it and a question on it while it is fresh.
The rules
Driving on underinflated or overinflated tires, or tires with low tread, can lead to safety issues on the road.
Tires are the only part of the car touching the road, and the problems they cause arrive suddenly.
Driving on underinflated or overinflated tires or tires with low tread can lead to safety issues on the road.
Kentucky tells drivers to check tire pressure with a pressure gauge monthly.
A tire can lose most of its pressure without looking flat, so the gauge is the only way to know.
Check Tire Pressure with a Pressure Gauge Monthly
The correct tire pressure for a vehicle is on a sticker on the inside jamb of the car door, marked PSI.
The number on the tire wall is the maximum the tire will take, not the number the car wants.
Open your car door; on the inside jamb, you should see a sticker.
Tire pressure should be checked when the tires are cold.
A tire that has been driven on is warm, and a warm tire reads high, so the number is wrong.
Remove the cap from the valve stem and use the pressure gauge to check the tire pressure (make sure you check when they are cold)
To check tread depth with a penny, a driver holds Lincoln's body between thumb and forefinger and places his head first into the deepest-looking groove.
A coin is always in the car, which is why this check is the one people actually do.
Check Tread Depth with a Penny
If all of Lincoln's head can be seen in a tire groove, the tires are too worn and should not be driven on.
Seeing the whole head means the tread is gone, and worn tires are what turn a wet road into a slide.
If yes, your tires are too worn—don’t drive on them, and make sure to get them replaced.
On the test
What does Kentucky say driving on underinflated tires can lead to?
Safety issues on the road. Tires are the only part of the car touching the road, and the problems they cause arrive suddenly. Kentucky Driver Manual, p.28: “Driving on underinflated or overinflated tires or tires with low tread can lead to safety issues on the road.”
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Where these come from
Every rule here is checked against Kentucky Driver Manual, published by the Kentucky Transportation Cabinet, and against the state code itself. Last checked 2026-09-16.
- src/assets/drivers-manuals/KY.pdf (Kentucky Driver Manual, Kentucky State Police / Kentucky Transportation Cabinet, retrieved 2026-09-14; no edition statement in the document)
- src/assets/drivers-manuals/KY.pages.txt (plain pdftotext over that PDF; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/SOURCES.json (sha256, folio offset 8, folioMarker, nonLawPages, the extraction flag and knowledgeTestBasis, each with its basis)