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What Makes for a Street Legal Vehicle?

Many of us have drooled over exotic racing cars, fantastic movie prop vehicles, or futuristic looking concept cars, only to learn that we could never own one for our daily commutes (as though money were no object) because it is not “street legal.” What does that mean? What is required for a vehicle to be considered “street legal?”
Generally, “street legal” means having whatever equipment or features the law would require to allow one to operate it legally on the roads at any time and without restriction. Obviously, it is possible to operate vehicles on the road with special permission under certain circumstances, but this is not what one usually means by “street legal,” so we will ignore those scenarios for now.

The first problem with a definitive list of street legal features is that each state is allowed to control the standards for vehicles that operate on roads in its jurisdiction. As a result, for example, California has some of the strictest emissions standards in the U.S., and a vehicle which may be perfectly acceptable to drive (smoking tail pipe and all) in Florida will not be acceptable in California. However, there are a number of general characteristics that all vehicles must have to be legal in every state in the U.S.:

Horn – It may not seem the most important piece of safety equipment, and many big cities even limit how it can be used, but to be street legal every vehicle must have a horn that is audible for at least 200 feet. The horn can generally be any note or sound (even ones that play musical tunes are usually permitted), so long as the minimum volume requirements are met.

Engine Hood – It may be surprising that having a hood is mandatory to be street legal, but it is. Indeed, even the hood scoops or air intakes on the hood are regulated and can be no more than 4 inches higher than hood surface in most jurisdictions.

Windshield – Another mandatory item, though this one is easier to understand: windshields keep debris out of the driver's eyes. Most states do not allow any tinting of the front windshield, or only a small portion, and side windows must allow between 40% and 70% light transmittance, depending on the state. Many prohibit mirrored tinting entirely.

Windshield Wipers – This is another obvious need, particularly when driving in rain or snow.

Mirrors – Requirements for mirrors vary by vehicle design, but usually the bare minimum will be two mirrors. In most cars this will be a driver's side and interior rearview mirror, and in box trucks or other vehicles where an interior mirror's view would be obstructed, two outside mirrors (one on either side).

Steering Wheel – You might be thinking this is not only a necessity to be street legal, but also to be drivable, but really these laws limit the types of steering wheels. To be street legal, one cannot have a “butterfly” shaped steering wheel or a fighter jet like joystick. Instead, a vehicle must have a circular wheel at least 13 inches along its outside diameter.

Seat Belts – Every state requires the use of seat belts when operating or riding in a motor vehicle, so, of course, their inclusion in the equipment of a vehicle is mandatory.

Brakes – Again, this is a no-brainer for the most part. The added twist many do not consider is it is also necessary to have a functioning parking brake.

Tires – Most vehicles will meet tire requirements when leaving the showroom floor, but to be street legal, the tires must be installed in such a way as to reduce the danger of discharging debris toward following vehicles. When building a vehicle from scratch or modifying an existing one, the rule of thumb is that the rear tires of a vehicle must have the top half covered by mud flaps (fenders usually qualify).

Mufflers and Exhaust/Emission Control Systems – Some drivers dislike exhaust and emission control systems because they can have a negative effect on engine performance. However, they were mandated to control pollution and are required for a vehicle to be street legal. Similarly, mufflers cannot be removed, both because of noise pollution and because they often play a role in the emissions control process. Additionally, because these components become very hot during operation, they must be located in such a way that a passenger is not able to burn themselves getting in or out of the vehicle.

Lights – To comply with the Department of Transportation's requirements, every vehicle must have headlights, tail lights, stop lights, and turn signals, all housed in DOT approved covers and using approved bulbs. Headlights must have at least 22 inches of ground clearance and all lights must be of the approved colors allowed by the DOT. Many states limit obstructions of the lights or the use of lighting on the undercarriage, hood, or wheels.

License Plate – Every vehicle has to have a spot to carry a license plate, and that location must be lit. Although a number of products have come on the market in recent years to combat automatic cameras designed to catch toll booth violators and those who run red lights, these are largely illegal as one cannot obstruct the view of the license plate and it must be visible from 100 feet. Some states require more than one license plate (front and back), while others merely require the one in the rear.

Reflectors – If you have ever spotted a car parked on the side of the road even though its lights were off, it was thanks to reflectors. To be street legal, a vehicle must have side and rear reflectors (often integrated into the lights). Side reflectors must be amber, and rear reflectors must be red.

Bumpers – One of the first safety measures, and still required in all vehicles.

So those are all of the things a vehicle has to have to be street legal, but what about things it is not allowed to have?

Evasion Devices – Obviously, anything designed to allow for evasion of law enforcement by obscuring views or damaging other vehicles is generally going to be illegal, so no smoke screens, caltrops, or oil slicks. Some jurisdictions also limit the use of radar detectors or jammers.

Low Riders – Many states have minimum street clearance requirements for a vehicle to remain street legal. How that clearance is measured varies. Sometimes it is the body clearance, sometimes it is the size of the wheel rims. Other states prohibit or restrict hydraulic lift suspensions. Shocks cannot be removed to achieve the desired height.

Lifts – Vehicles that have oversized tires, elongated suspension, and “lift kits” installed may also be considered illegal in some jurisdictions. These modifications affect rollover stability and the potential for riding over other vehicles. As a result, every state has some limitation on how big is too big to be street legal.

More Information

If you would like more information about whether your vehicle is street legal (or will be after some planned modifications) you should contact both your state's department of motor vehicles and an attorney. The DMV cannot give you legal advice, only an attorney can do that, and it might be useful to know exactly what your rights may be in the event you are stopped for one of your modifications.