Q. I bought a small two-wheel-drive pickup truck at a local Rhode Island car dealer for my son. I filled out all the forms they gave me for the registration and left a check as requested made out to the DMV. They put my son’s old plates (from his Camry) on the truck and told me I was good for three days and to stop by the next day and get the final registration.

Later that night my son was pulled over and the truck impounded for illegal use of plates. Does the rule that allows the temporary use of the old plate require it be a combination plate for the three days? The insurance had been transferred and the cards were in the vehicle along with the bill of sale from the dealer. The dealer was very helpful and took care of the tow but my son still has a ticket that we need to go to court for and I could not find the section of the rules online to check the current laws.

A. The section that you are looking for is 31-4-3 Temporary registration — Invoice voucher issued by dealer, which states, “…(a) Any person who purchases a motor vehicle from a bona fide licensed dealer and who presently has a motor vehicle registered in this state, may, when the vehicle purchased is of the same type as the presently owned and registered vehicle, operate the newly acquired motor vehicle for a period of twenty (20) days following the date of the original dated voucher. During this period any operator of the newly acquired vehicle shall carry the original dated bill of sale or invoice voucher which shall be accompanied by a numbered state sales tax form. The voucher or bill of sale shall recite the registration number to be transferred from the former vehicle to the newly acquired vehicle.

The key words in that statute are “when the vehicle purchased is of the same type as the presently owned and registered vehicle…,” which, as you have described the situation, was clearly not the case. A passenger plate cannot be used on a vehicle that, by law, must be registered commercial or combination, nor could a commercial plate be put on a passenger vehicle for the 20 days outlined in the law.

Gina Antonucci Zanni, supervisor of communications for the State Division of Motor Vehicles, has agreed to answer questions of general interest posed by Journal readers about state motor vehicle laws and procedures. To ask a question that would also be of interest to other readers, send a letter to Ask projoCars, Features Department, The Providence Journal, 75 Fountain St., Providence, RI, 02902. You can e-mail your question to projocars@projo.com. Please put “Ask projoCars” in the subject field. Questions or complaints of a specific nature should be posed to the DMV directly and will not be answered in this column.

Confused about road rules? Or looking for a low-number license plate? You’ll find an archive of official answers to past driving questions posed by Journal readers at projocars.com