Seat Belts, Child Restraints, Defensive Driving, Distraction and Traffic Stops: How to Wear a Belt, Air Bags and the Ten-Inch Rule, Who the Belt Law Covers, the Four Child Restraint Classes, Defensive Habits, Posture and Hand Position, the Three-Second Rule, Space Behind and to the Side, Tailgaters, Stopping Distance, Signaling, the Horn, Slow-Poke Driving, Carbon Monoxide, Deer, Tire Pressure and the Penny Test, What to Do When Police Stop You, Distractions and the Hands-Free Phone Law

Written for aiforu2 as the source for a practice-test bank and the on-device tutor for the Missouri written test. The facts follow the official manual; the wording is ours.

Source: Missouri Driver Guide (Department of Revenue, revised August 2026), Chapter 8 "Safe Driving Tips for Everyday Driving" (pages 55–62) and Chapter 16 "Distracted Driving and Electronic Communication Devices" (pages 92–93).

Seat belts and air bags

Buckle up before you drive and make sure every passenger is belted or in a child restraint; belts greatly cut the chance of injury or death. Wear the lap belt low and snug across the hips and the shoulder belt across the chest, never under the arm or behind the back, and use both parts of a two-part system. Wear the belt even with air bags: an air bag protects against the steering wheel, dashboard and windshield but not in a side or rear impact or a rollover, and it will not keep you behind the wheel. An unbelted or badly belted occupant can be seriously hurt or killed by a deploying air bag; the National Highway Traffic Safety Administration recommends at least ten inches between the center of your breastbone and the center of the steering wheel. Children 12 and under ride properly restrained in the rear seat, and a rear-facing infant seat never goes in front of a passenger air bag.

Missouri law requires the driver and front-seat occupants of passenger vehicles to wear properly adjusted, fastened belts, and all passengers riding with an intermediate license holder must be restrained.

Child passenger restraints

The law applies in any vehicle except a public carrier for hire or a school bus. A child under four, whatever the weight, and any child under 40 pounds, whatever the age, rides in an appropriate child restraint. A child four to seven who weighs 40 to 79 pounds and is under 4 feet 9 inches rides in a child restraint or booster seat. A child who is at least eight, or over 80 pounds, or taller than 4'9" may use a seat belt or a booster.

Defensive driving

To avoid your own mistakes and other people's, keep your eyes moving: watch ahead and to the sides and check your mirrors every few seconds, paying special attention to oncoming vehicles, since many head-on crashes come from distracted drivers crossing the center line. Expect other drivers to make mistakes and plan for them; do not assume a vehicle approaching a stop sign will stop. Never cause a crash on purpose even when someone fails to yield to you. Do not rely on signs and signals to hold others back; look left and right at every intersection even when cross traffic has a red light or stop sign.

Posture and steering

Sit upright with your back against the seat, close enough to reach the pedals easily but far enough that your elbows are in front of you on the wheel, both feet within reach of the floor controls and both hands on the wheel. Hold the wheel with the left hand between seven and nine o'clock and the right between three and five o'clock, look well down the road, turn corners hand over hand rather than with one palm, and straighten out by hand afterward. Never turn the ignition key to the lock position while the vehicle is moving; the steering wheel will lock and you will lose control.

Following distance and space

Rear-end crashes are common and come from following too closely. Use the three-second rule: pick a fixed object ahead, and when the vehicle in front passes it count "one-thousand one, one-thousand two, one-thousand three"; if you reach the object first, you are too close. Help the driver behind keep a safe distance by holding a steady speed and signaling early when you slow. Find a spot out of traffic to pick up or drop passengers; before parallel parking with traffic behind, signal, stop beside the space and let them pass; if you must drive slowly, pull over or use turnouts and passing lanes so others can get by. If you are tailgated, move to the right lane if there is one; otherwise wait for a clear road ahead and slow gradually so the tailgater goes around. Never brake suddenly to discourage one; that only raises the risk of being hit.

Keep space on both sides. Avoid driving beside other vehicles on multi-lane roads, stay away from the center line on two-lane roads, drive in the center of your lane, move over a lane for vehicles entering, leave extra room beside parked cars for opening doors and people stepping out, give pedestrians and bicyclists extra room, and take hazards one at a time: if you are overtaking a bicycle while a vehicle approaches, slow and let the vehicle pass first.

Stopping distance

Your stopping distance is your reaction distance (how far you travel between seeing a danger and applying the brakes; the guide's chart assumes a 1.5-second reaction) plus your braking distance (from brake application to a stop, for good brakes and tires on a good dry road). Speed, fatigue and bad brakes all lengthen it.

Signaling and the horn

Signal before every lane change, turn, merge and parking move, even when no one seems to be around, and at least 100 feet ahead. If there are streets, driveways or entrances between you and your turn, or a vehicle about to enter between you and the turn, wait until you have passed them before signaling so you do not mislead anyone. After the move, make sure the signal cancels; after a slight turn it may not. Use the horn only when you must, to warn another driver, never as a show of anger; needless honking distracts others and can cause a crash.

Slow driving and carbon monoxide

Driving slower than a posted minimum under normal conditions is illegal, though bad weather, heavy traffic or a bad road justify it. Even without a posted minimum, driving so slowly that you block traffic is illegal; pull over and let the line pass. Slower is not always safer. Engine exhaust carries deadly carbon monoxide, so never run the engine in a garage, in a parked vehicle with the windows closed, or with the heater or air conditioner on while parked and shut up; close the vents when following closely; and do not drive with a faulty muffler or exhaust.

Deer

Slow and stay alert near deer crossing signs and around fields, streams and gardens; deer seldom travel alone, so one deer means others. Most deer crashes happen in January, May and October through December, with the highest risk from sunset to midnight and around sunrise. After dark use the high beams when no one is coming, because they light up deer eyes. If a crash is unavoidable do not swerve, and check behind you before braking hard, since heavy braking drops the front end and can send the animal into the passenger compartment. Afterward report to local law enforcement, get a police report for the insurance claim, and tell a Department of Conservation agent where it happened.

Tires

Check tire pressure before driving against the PSI in the owner's manual or on the driver's door jamb, using a gauge, and add or release air to match. Check tread monthly and before long trips with the penny test: put Lincoln's head into the shallowest groove; if any part of the head is covered, the tread is safe, and below about 2/32 of an inch grip in bad conditions falls sharply.

When police stop you

Officers stop drivers for observed violations or investigations. When you see the emergency lights, stay calm, signal, pull off or to the side as soon as it is safe, turn off the ignition and radio, stay in the vehicle unless told to get out, keep your hands on the wheel where they can be seen, ask passengers to stay calm with their hands in view, put phones away, make no sudden moves, and do not reach for documents until asked. If you have a weapon in the vehicle, tell the officer at first contact. At night turn on the interior light. The officer will usually say why you were stopped; an officer not in uniform will show credentials, and you may ask. Tell the officer where your license, insurance and registration are before you reach for them. If asked to get out, stay clear of traffic with your hands visible. Your signature on a ticket is not an admission of guilt, but refusing to sign can lead to arrest; argue in court, not at the roadside, and report any misconduct to the officer's agency. You keep your constitutional rights: freedom from unreasonable search and seizure, the right to remain silent, and the right to an attorney.

Distracted driving

Driving needs your full attention. Distractions include texting, phone use, grooming, reading (maps included), eating and drinking, watching video, talking to passengers, adjusting audio, using navigation and surfing the Internet. Texting is the highest-risk distraction because it takes your eyes, hands and mind at once, and reading, writing or sending a text or electronic message while driving is illegal. Children, friends and pets all distract: pull over to deal with children, hold arguments elsewhere, and secure pets in a carrier, kennel or harness, never on your lap. Adjust mirrors, seat, climate and radio before you drive, check messages before leaving or after arriving, set an auto-reply saying you are driving, use normal stops for adjustments and let passengers handle the controls. Staring at a crash scene, billboard, stopped vehicle, construction or scenery is a distraction too.

The electronic communication device law

No driver of a commercial or noncommercial vehicle may use an electronic communication device on a highway or on property open to public traffic. While the vehicle is moving you may not physically hold or support a phone with any part of your body, manually type, write, send or read text-based messages, record, post, send or broadcast video (video calls and social media included), or watch a video or movie. You may place or take voice calls with hands-free or voice-operated functions that need a single touch or swipe, talk hands-free through a speaker, Bluetooth or an earbud, send and receive texts by voice-to-text, use GPS navigation, music and podcasts, view a map for navigation, listen to audio, or, as a transportation-network driver, relay information through a device mounted to the vehicle. Violations before January 1, 2025 could draw a warning; after that date they are an infraction, commercial drivers may face disqualification, and fines and criminal penalties may apply.

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