Tire care — Missouri Permit Test

Tire care on the Missouri permit test — 4 rules, each with the reason behind it and a question on it while it is fresh.

The rules

Check your tire pressure against the recommended PSI in the owner's manual or on the driver's side door jamb.

The number on the tire itself is a maximum, not a recommendation. The door jamb is where the right figure is.

check the tire pressure using the recommended PSI (pounds per square inch) located in the vehicle owner’s manual or the driver’s side door jam of the vehicle

Missouri Driver Guide, p.60

You may measure tread depth using the penny test, checking once every month or before a long road trip.

It costs a cent and thirty seconds, and it is the difference between gripping and not.

Once every month, or before you embark upon a long road trip, check your tires for wear and damage problems.

Missouri Driver Guide, p.60

If any part of Lincoln's head is covered by the tread in the penny test, you have a safe amount of tread.

The coin gives you a yes or no answer without needing a gauge or a garage.

If any part of Lincoln’s head is covered by the tread, you’re driving with the safe amount of tread.

Missouri Driver Guide, p.60

Tread below roughly 2/32 of an inch greatly reduces your car's ability to grip the road in adverse conditions.

Two thirty-seconds is where a tire stops clearing water and starts riding on top of it.

If your tread gets below that, (approximately 2/32 of an inch) your car’s ability to grip the road in adverse conditions is greatly reduced.

Missouri Driver Guide, p.60

On the test

Where is the recommended tire pressure for your vehicle found?

In the manual or on the door jamb. The number on the tire itself is a maximum, not a recommendation. The door jamb is where the right figure is. Missouri Driver Guide, p.60: “check the tire pressure using the recommended PSI (pounds per square inch) located in the vehicle owner’s manual or the driver’s side door jam of the vehicle”

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

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All Missouri permit topics

Where these come from

Every rule here is checked against Missouri Driver Guide, published by the Missouri Department of Revenue, and against the state code itself. Last checked 2026-09-16.