HIGHER SPEED LIMITS on the highways mean, unhappily, more deaths. Last April Congress decided to let states raise the limits from 55 miles an hour to 65 on rural sections of the interstate system. Now the first reports of the consequences have appeared. They are fragmentary and preliminary, but ominous.

They are provided, not entirely voluntarily, by the National Highway Traffic Safety Administration because Congress wanted them. NHTSA surrounds them with many cautions that they cover only three or four months, that they don't include the whole country and that they don't consider other factors, such as increased driving. Fatalities also rose, although not nearly so much, in states that have not changed their speed limits, and there are wide variations from state to state. That's all quite true, and yet . . .

In 22 states that chose to raise their speed limits last spring, there were 450 fatalities on the rural interstates from May through July. In the same period the year before, on the same roads, the number of fatalities was only 296. That's an increase of 52 percent.

On the other roads in the same 22 states, where the speed limits were unchanged, the number of fatalities fell from 4,830 in those three months of 1986 to 4,350 this year. The safest roads in the country are now getting more dangerous because of higher speeds, while the more dangerous state and urban roads are getting safer.

Can you think what the reaction would be if Congress had made a change in air safety regulation that produced a sharp increase in fatalities on certain routes? But people seem to think of air safety and highway safety as two entirely unrelated subjects, and do not find it strange that public policy should apply totally different standards to them. Even before Congress changed the rules, your chance of being killed, per mile of travel, was a dozen times higher in a car than in a scheduled airliner. And yet most of the world continues to cherish the belief that air travel is inherently dangerous while driving -- even at 65 -- is safe.

Preliminary and incomplete though these highway death statistics are, perhaps they will at least accomplish one purpose. Perhaps they will give second thoughts to some of the people in Congress who have been pushing to extend the higher speed limits to more roads.