The Times is publishing a series of articles highlighting common laws and rules. Today, we examine vehicle add-ons, like lighting and tinted windows. To suggest a law for The Times to highlight, contact the writer.

A lot of people add perfectly-legal accessories to their vehicles, like remote starters or bug shields. But other add-ons -- like tinted windows, extra lighting and even window stickers -- could get a person pulled over by police.

Window tinting, for example, comes in legal and illegal shades. Indiana law states it is illegal to have windows "tinted to the extent or manufactured in a way that the occupants of the vehicle cannot be easily identified or recognized through that window from outside the vehicle."

Porter County Sheriff's Department Sgt. John Kuehl said the law is designed to protect police officers, since they need to know who and what is in a car that they stop.

The law does allow dark tinted windows if they're needed for medical reasons, as long as the person carries a doctor's note with them. Violations are less frequent than they used to be because most shops know not to install illegal tints, Kuehl said.

People should also be careful when adding additional lighting to their cars, because it is illegal to put on lighting that could be confused with the emergency lighting used by police officers, firefighters and medics.

It is also illegal to drive around with the headlights that are on a pickup truck's roll bar activated. Indiana law stated headlights must be between 24 to 54 inches off the ground.

Indiana law also requires people to drive safe, well-maintained vehicles. This is accomplished through requirements calling for things like exhaust systems, windshields, windshield wipers and lights.

"The biggest (equipment violation) people probably get stopped for is having a headlight or taillight out," Kuehl said.

But Kuehl believes the fact vehicles in Lake and Porter counties need to undergo emissions testing keeps a lot of vehicle with bad exhaust systems -- and usually other defects -- off the road.

"You don't see the real clunkers you used to see on the road," Kuehl said.

Motorists also need to be careful stickers they put on their car windows don't obstruct their view on the windshield, side windows or rear window. Indiana law prohibits "non-transparent material" covering the window, with the exception being a sticker of less than 4 inches on the windshield.