Hawaii’s vehicle tinting businesses could see a boom if a bill becomes law allowing vehicle owners to have darker window tinting.

Tinting replacement business will increase because vehicle owners prefer darker tinting, Ronald McCullough, owner of Midnight Tinting, told the Honolulu Star-­Advertiser at his shop on Sand Island Access Road.

If House Bill 23 becomes law, “Every customer we have is gonna want to come in and change their tint,” McCullough said.

At Midnight Tinting, prices range from $340 to $500 depending on the type of film and the make and model of the vehicle.

Allowing vehicle owners to darken their windows from current state law worries the Honolulu Police Department.

Acting Maj. Stason Tanaka of HPD’s Traffic Division said regulating window tint is important because it can impair a driver’s vision, especially at night.

“This decreased visibility can contribute to collisions,” Tanaka said.

Darker-tinted windows also could affect the safety of HPD officers who have to approach a driver’s window, unable to see what’s happening inside, Tanaka said.

“We will be monitoring the bill,” Tanaka said. “The darker the tint would hamper the ability of officers to clearly see into the vehicle, to monitor what is in the vehicle, for officers’ safety.”

Currently, the fine for having a lower tint percentage than the allowed amount is $287, according to HPD.

HB 23 would change the “light transmittance requirement” to 20% from 35%, meaning only 20% of light would be allowed in the vehicle.

“So 35% means it’s reflecting 65% light, so it’s letting in 35%,” McCullough said.

At the proposed 20% change, 80% of light is reflected, letting in 20%, he said. “The lower number you go, the darker the film gets,” McCullough said.

State Rep. Scott Nishimoto (D, Moiliili-McCully) introduced HB 23 on behalf of a constituent.

“By law, only representatives and senators can introduce bills,” Nishimoto said. “I’ve had a policy where I introduce bills for constituents because they have no other way to actually get them introduced except through their representative.”

McCullough supports HB 23 — and so do most of his customers, he said.

“Most people want it darker because of the year-round sun we have and how hot it gets,” McCullough said. “It looks better, it helps people stay cooler, it keeps things more private because there’s a lot of smash and grab going on. A lot of people are getting things stolen from their vehicles.

“It’s still very easy to see out the windows with 20% on,” McCullough said. “In fact, I feel it’s the perfect percentage for vehicles.”

Hawaii does have leeway regarding tinting, McCullough said. The tint can be plus or minus 6% on the windows, except for the front windshield, he said.

Any percentage is allowed for SUVs, trucks and vans on the rear windows, but the driver and passenger windows have to be at 35%, plus or minus 6%, McCul­lough said.

“It makes sense for everybody,” McCullough said. ”The rear windows of SUVs already come at 20%, so why not allow it?”

Although the change will improve business, McCul­lough said he doesn’t like taking off tint.

“Not to be negative, we just don’t like taking off tint, but that’s just what it is and what’s gonna happen,” McCullough said.

The tinting business is big but inconsistent in Hawaii. McCullough estimates there are about 30 to 40 tinting shops on Oahu, “like five to 10 that (are always open during the day).”

He said an estimated unknown number of people install tinting out of their homes and carports.

“A lot of people say, ‘If I’m going illegal, I might as well go all the way and go with 5%,’” McCullough said.