On Friday, Walter Douglas of our Maryland-Virginia desk showed me a UPI story about snow-tire rules.

It said that Maryland's motor vehicle administrator, William Bricker, will hold a hearing on Dec. 22 "to decide whether motorists should be allowed to use radials as snow tires." It added: "Currently, motorists must have snow tires on their cars on days designated as snow emergency days. Radials do not qualify as snow tires."

Walter asked, "Is that correct?"

I said, "No. Some radials have qualified as snow tires for years."

Walter said, "That's what I thought. But Maryland is the state that gives you a ticket for not having snow tires even if you don't get stuck, isn't it?"

"You have a good memory," I told him. "In most jurisdictions, if you can get through without tying up traffic, they don't care what kind of tires you have. Maryland is different."

Each state has its own snow rules, and they vary widely. In some, snow regulations become effective whenever it snows, but in most they become operative only when an official snow emergency is declared. In some cities the rules apply to all roadways, but in most they apply only to designated major arteries.

The District of Columbia used to have no time limit on its snow-tire law. If it snowed in May (as it has in this area) and a motorist got stuck, he could also be stuck with a traffic citation. The D.C. snow-tire law now is limited to the period between Oct. 15 and April 15. It doesn't say your car must be equipped with snow tires; it merely says that if you get stuck you can be ticketed for not having chains or snow tires. Impeding traffic by running out of gas is also illegal.

Each state defines "snow tire" as it wishes. In Maryland, a tire can become a snow tire in three ways: by the manufacturer's designation that it meets snow tire stardards, by being declared a snow tire by the motor vehicle administration and by undergoing microsiping. You won't find miscrosiping in Merriam-Webster III, but you will find the noun sipe , a reference to tire tread designs that give improved traction.

Steve Horwitz, public information officer for Maryland's Motor Vehicle Administration, told me that many conventional radials are accepted in Maryland as snow tires -- e.g.: GM cars equipped with all-season radials that bear the letters "TPC" followed by a four-digit number. Special snow tire radials (radials with deep treads) are also accepted.

D.C. traffic engineer John McCracken says the District follows guidelines set by the rubber manufacturers' trade association. Radials marked M/S (for mud/snow) are accepted as snow tires.

I thought I knew what Virginia law says about snow tires, but I made the mistake of trying to double-check it with the Arlington commonwealth attorney's office. A young man there said he would put me on "hold" while he phoned the police to ask them what the law says. When I protested that I wanted a lawyer's reading of the law, not a policeman's, he told me I'd have to call Commonwealth Attorney Henry Hudson.

Hudson was in a meeting. Time passed. He didn't call back. At 4 p.m. Friday, I phoned again to say I needed to talk to somebody before quitting time. If Hudson wasn't available could one of his assistants tell me what the snow-tire law says?

That won me the rare privilege of talking to an assistant who fluffed me off to the Department of Motor Vehicles. "I don't know the law," he explained. "I'd have to look it up."

He made "look it up" sound like an utterly unreasonable request.

By that time it was 4:31 p.m., and DMV didn't answer its phone, so I began calling police departments.

Fairfax said tires marked M/S were acceptable, but some all-season tires were not. Alexandria said all-season tires (Tiempo was mentioned as an example) are accepted as snow tires. A man on the Arlington police "information" number said, "It's a very ambiguous law, but it does say that if a snow emergency is declared and you get stuck and impede traffic, you will get a ticket if you are not equipped with chains or snow tires. And I'm sorry to tell you that conventional-tread all-season radials are not accepted as snow tires in this state."

Before snow flies, I will try to find lawyers who can make the Virginia snow regs a little less ambiguous for us, but I offer no promise I'll succeed.