Most of the time, a car carries people.
Every so often it becomes a moving truck, a camping hauler or a lumber cart from the home store.
Those are the trips when drivers take shortcuts.
They tie a mattress to the roof with a single cord or stack boxes up to the ceiling.
Some even let a dog ride loose in the truck bed.
These choices can cause crashes, tickets and injuries to people who never saw it coming.
This guide explains the rules for carrying cargo, keeping your view clear and transporting passengers and pets.
The rules come from the California Driver Handbook.
Other states have similar laws, so check your own state handbook for the exact limits.
Rule one: you must be able to see and steer
The California Driver Handbook starts with a simple principle.
You must not drive a vehicle so overloaded that you cannot control it.
You also must be able to see ahead and see to the sides.
A car packed to the roof can hide the rear window and block both side views.
If you cannot see out the back, rely on both side mirrors and adjust them before you leave.
Better still, repack so the rear window stays clear.
Weight changes how a car drives
A heavy load does more than fill space.
It makes the car slower to stop and less stable in turns.
Brakes have more weight to slow down, and the suspension leans more in curves.
Leave extra following distance when the car is full.
Our guide to the three-second rule explains how to measure that distance.
Check your owner's manual for the maximum load and the correct tire pressure for a full car.
Rule two: secure everything
The handbook says you must not drive with an unsecured load that is a safety hazard.
A box sliding off a roof rack at highway speed becomes a hazard for every driver behind you.
Loose items inside the car are dangerous too.
In a hard stop, a heavy object on the back seat keeps moving forward.
How to secure a load
- Use proper straps rated for the weight, not light rope or bungee cords alone.
- Tie loads to fixed points on the roof rack or truck bed.
- Put heavy items low and toward the front of the cargo area.
- Cover loose material such as mulch or yard waste with a tarp tied at every corner.
- After the first few miles, pull over safely and check the straps.
Straps often loosen as the load settles, especially on a roof.
Loads that stick out
Long items like ladders, lumber and kayaks often stick out past the car.
The handbook sets clear limits for passenger vehicles.
- Nothing may stick out beyond the fenders on the left side.
- Nothing may stick out more than six inches beyond the fenders on the right side.
- Cargo that extends more than four feet past the rear bumper needs a flag.
The flag must be a red or fluorescent orange square at least 12 inches on each side.
At night, that cargo must be marked with two red lights.
These markers help drivers behind you judge where your load really ends.
Without them, a following car may not notice a pipe until it is too late.
Wind and tall loads
A tall roof load acts like a sail.
The handbook's safe driving section warns that high winds are a hazard, especially for trucks, campers and vehicles with trailers.
On a windy day, slow down and keep a firm grip on the wheel.
Our article on driving in high winds covers that situation in detail.
Keep your windshield clear
Many drivers collect stickers, parking passes and air fresheners over the years.
The handbook says you must not put signs or objects on the front windshield or side windows that block your view.
Do not hang objects from the rearview mirror.
It lists the only places where items may be attached:
- A seven-inch square in the lower corner of the passenger side of the windshield.
- A seven-inch square in the lower corner of the rear window.
- A five-inch square in the lower corner of the driver's side window.
- A five-inch square at the top center of the windshield, for an electronic toll device.
- The side windows behind the driver.
A small object hanging from the mirror can hide a pedestrian at exactly the wrong moment.
Move parking permits and decorations to the allowed areas.
Screens and monitors
The handbook also limits screens the driver can see.
A video monitor visible to the driver may only show vehicle information, navigation, a media player or the radio.
Movies and videos should only be visible to passengers.
People in pickup beds
Riding in the back of a pickup can look like fun on a warm day.
It is also extremely dangerous in any crash or sudden stop.
The handbook says you must not let a person ride in the back of a pickup or other truck.
The exception is a vehicle with secure seats and seat belts in that area.
An open truck bed has neither, so passengers belong in the cab.
Pets on the road
Dogs love the open air, but a truck bed is no place for a loose animal.
The handbook says animals in the back of a pickup must be properly secured.
That prevents them from falling, jumping or being thrown out of the vehicle.
A crate tied down to the truck bed is one option.
Inside a car, a loose pet can distract you and can be hurt in a sudden stop.
A secured crate or a pet harness clipped to a seat belt keeps everyone safer.
The handbook adds that abandoning an animal on a highway is a crime.
It can bring a fine of up to $1,000, six months in jail or both.
A few more rules worth knowing
- Do not smoke in the car when a minor is inside. You can be fined.
- Never throw a cigarette or anything burning from your car. It can start a wildfire.
- Keep your license plate clean and readable, and never alter it.
These rules seem small, but each one protects someone on or near the road.
Before you pull away: a loading checklist
- Can you see out the windshield, the mirrors and the side windows?
- Is every heavy item low, forward and tied down?
- Are roof loads strapped to fixed points with rated straps?
- Does anything stick out past the left fender or more than six inches on the right?
- Does anything stick out more than four feet behind? Add the flag, and lights at night.
- Is the windshield free of hanging objects and stickers outside the allowed areas?
- Are pets secured and are all passengers in real seats with belts?
The bottom line
Hauling cargo safely is mostly about a few minutes of preparation.
Tie the load down, keep your view clear, mark long items and give yourself extra stopping distance.
Those few minutes protect you and every driver who ends up behind your load.
Sources and Further Reading
- California DMV: California Driver Handbook, Section 7, Laws and Rules of the Road (Continued) — supports the rules on overloaded vehicles, unsecured loads, cargo limits and flags, windshield objects, video monitors, people and animals in pickup beds, abandoning animals, smoking with minors and license plates.
- California DMV: California Driver Handbook, Section 8, Safe Driving — supports the warning about high winds for trucks, campers and vehicles with trailers.