PROVIDENCE — To end a sometimes-infuriating flaw in the state’s car registration system, the Division of Motor Vehicles is retiring its traditional way of assigning numbers and letters to passenger vehicles and shifting, at least temporarily, to unique all-numeric plates.

The plates are the same as the current wave design, except for the all-numeric format. The DMV started issuing them in December and reckons that the roughly 300,000 numeric plates available will last four or five years — long enough to replace the aging computer system that is part of the problem.

Agency spokeswoman Gina Zanni said the change is intended to put an end to issuing new plates that duplicate old ones that have expired but are still being used illegally.

In the past, she said, when a registration expired, the division waited six months and then, if the plate wasn’t re-registered, issued that same number-letter combination to another car owner.

But that didn’t keep the holder of the original plate from continuing to use it if he didn’t mind the risk of arrest. And if the former owner of the plate got lots of parking tickets, the owner of the new plate was held responsible.

The result was “a terrible inconvenience” for the victim and it cost DMV staffers hours and hours to untangle, she said.

Zanni said she knew of a case where a man was being hounded for tickets issued in the middle of the night on a Providence street where he never parked. She said he went there, found the car with the expired plate identical to his own and photographed it to prove his innocence. (He didn’t have to do that, she said. “We have investigators for that.”)

She said that in another case, a Rhode Islander had his car immobilized (“booted”) and towed in New York City and was forced to take a bus back to Rhode Island because a duplicate plate was being used and abused in New York.

There are slightly more than 1.1 million vehicles registered in the state, including 650,000 passenger vehicles. Those are the ones getting the new plates because those have the most problems, DMV officials said.

The traditional format for passenger vehicle registrations has been two letters, a space and three numbers, such as AB 125. The division started issuing the all-numbers plates starting with 710001. DMV administrator Brian Peterson said the agency tried plates with six digits in a row, but judged them hard to read and added a dash, as in 710-001.

The DMV started above 700,000 because that avoids the block of numbers used on the all-numeric commercial plates.

The last time Rhode Island issued six-numeral passenger registrations was in the 1930s, the DMV said.

The new system will affect only new registrations, Zanni said. Current plates will stay in use as long as they’re renewed and owners can transfer their existing plates to new cars. Other kinds of plates, such as commercial and suburban, aren’t affected and neither are vanity plates, she said.

“Rhode Islanders have a love affair with their license plates and they always have,” she said. Some people have been asking whether they’ll lose their current plates. They won’t, Peterson said.

The new system gives the DMV almost 300,000 new number combinations to work through without reissuing any plates. The DMV is issuing the new plates from its Pawtucket office, she said. The other DMV offices are using up their supply of the old plates before issuing the new ones.

Part of the reason for the switch, Zanni said, is the limited flexibility of the DMV’s aging computer system. For example, she said, the system can’t make a new, unique stock of registration numbers by switching the existing format around, for example to three numbers followed by a space and two letters, the reverse of the current format.

Partly as a result, the DMV has reused the same plates over and over. Peterson guessed that some have been re-issued two or three times.

Zanni said the new system will also prevent a time-consuming nuisance at the DMV. She said the computer system is unable to produce a list of registrations that don’t duplicate any currently registered plates. That means that before the DMV can order a list of new plates from the Department of Corrections, the list has to be checked by hand. The new system, she said, will allow the DMV to order a set of new plates from a list of consecutive numbers, confident that they won’t duplicate any current plates.

The General Assembly has appropriated $12 million for a new DMV computer system, Zanni said, and the agency is preparing a request for proposals from vendors. The new computer system should be flexible enough to allow other formats, such as reversing the current one and putting the letters last, she said.