ON THOSE LONG stretches of open highway in the West, the difference between driving at 55 mph and 65 mph is substantial. It cuts the length of time needed to travel 100 miles by about 17 minutes, no small saving when you consider the distance from Cheyenne to Rock Springs or form Casper to Jackson. So it is not surprising that a majority of the members of Wyoming's Senate has grown tired of the federally imposed 55-mph speed limit. It is boring, as well as difficult, to hold a high-powered car down to that speed when you are going to be driving all afternoon, or all day, across that state.

What is surprising is that the Wyoming senators seem prepared to give up $51 million in federal funds to raise the state's speed limit to 65. It may be, of course, that they think Congress will back down and repeal the law cutting off highways funds from states that permit speeds higher than 55. That might happen -- although it should not -- if enough other states reject the higher limit. Several other legislatures have proposals like the Wyoming bill before them.

Congress imposed the 55-mph limit in 1974 as a fuel-conservation measure, which it is; federal officials estimate it conserves about 9 million gallons of gasoline a day. But the speed limit has also turned out to be a major public health measure, perhaps the most effective life-saver ever passed by Congress. The best estimate is that it has helped save the lives of about 36,000 people in the last five years.

That reduction in highway fatalities has come about despite the reluctance of some states to enforce the 55-mph limit and despite the refusal of many drivers to abide by it. Proponents of raising the speed limit claim most of the reduction is due to things like seat belts and safer cars. But the facts are that accidents happen at 65 mph that would not happen at 55 mph, and that the odds of surviving a crash are many times better when you are driving within the legal limit than when you are exceeding it by any significant margin.

On that basis alone -- never mind the continuing energy crisis -- repeal of the existing limit by Congress, or by any state, would be foolhardy. The polls show 70 percent of the public think 55 is a reasonable limit. The evidence is that it keeps people alive and well who would otherwise be killed.Seventeen minutes per 100 miles is not a high price to pay for those lives.