A FRIEND of mine has a car with a chronically leaking tire that he has to pump up at least once a week. This has provided the opportunity to make an informal survey of gas stations in several cities. Three out of every four, he finds, don't have a working air pump. Air is harder to get than gas. It so happens that tire pressure is the greatest single factor affecting fuel economy; according to EPA, underinflated tires can cause a car to use 10 to 25 percent more gas. And almost all cars have underinflated tires. If we're really interested in saving fuel, we ought to require attendants to check the tires when they fill the tank. Such a law could go into effect immediately, involving no investment capital.

Time and again the bureaucracy, which can so often seem inept and lethargic, moves like a tiger when its own interests are threatened. Three recent illustrations:

1. It persuaded President Carter's pay advisory commission that the annual in-grade "step" increases given to 99 percent of federal employes shouldn't count as pay raises under the inflation guidelines.

2. It persuaded the Merit System Protection Board to invalidate a regulation permitting the firing of government employes for "unacceptable performance."

3. It effectively emasculated another intended result of the Civil Service Reform Act -- a study to determine how much of the government could be moved out of Washington -- by persuading the Office of Management and Budget to report that only a few thousand jobs could be moved to field locations without undue cost and disruption.

Last week it was reported that Amtrak's on-time record fell from 74 percent in 1976 to 57 percent in 1979. One reason is that many railroads sidetrack passenger trains in favor of their own freights. There is a federal law forbidding this practice, but until now no one has enforced it. I have the man for the job. He's Sheriff Larry Pamplin of Falls County, Texas.

It seems, according to Texas Monthly, that while Missouri-Pacific crews took their half-hour coffee breaks at a Falls County cafe, their freight trains were left blocking the streets, including the main route to the hospital. Pamplin and railroad officials had engaged in a war of words for months, but when the sheriff found his way to the hospital barred one day early this year, he'd had enough. Invoking an old state law prohibiting obstruction of a crossing for more than five minutes, Pamplin arrested the conductor and threw him in jail. Missouri-Pacific had to send another conductor to move the train. As a result, Pamplin says, things "have improved considerably."

The Russians are on to us. Here is an excerpt from an article by Aleksei Burmistenko appearing in a recent issue of the Soviet magazine Zhurnalist:

"On the whole, the use of 'leaks' is a dubious journalistic technique -- from both a professional and an ethical viewpoint. First of all, 'investigative reporting' rarely turns up anything of social significance. Unfortunately, more typical examples of what this method yields are the 'exposure' of the affair between Congressmay Wayne Hays and his secretary Elizabeth Ray (with all the salacious details) and the 'leak' of indecent remarks made by former Secretary of Agriculture Earl Butz.

"In the second place, in using 'leaks' press organs inevitably place themselves in the humiliating and dependent position of passive conduits for those who organize the 'leaks' -- congressmen, politicians, government officials. A reliance on 'leaks' or 'authoritative' sources makes it impossible for western journalists to evaluate and verify the information they obtain. In most cases, the logic of the bourgeois press calls for the immediate publication of a 'scoop.' Sometimes a publication receives a Pulitzer Prize for such a story, but usually this approach results in the tendentious coverage of events and divorces the press from responsibility for authenticity or consequences of its 'revelations.'

"The result is a vast number of 'overblown' sensations, false 'leaks,' and 'facts' taken out of context. For instance, if one glances back through the 'Periscope' and 'Washington Whispers' sections of Newsweek and U.S. News and World Report over the past few years, it is amazing how many absurdities, mistaken forecasts and unconfirmed 'facts' one finds."

A few months ago the government announced plans to require food labels to divulge more information about ingredients. I applaud the effort but wish it would broaden its sphere of concern. There's something else that many of us consume with some regularity that has no labeling information at all. Yet one hears that most beers contain sodium nitrate -- and that some European wines are filtered through asbestos. We have the drinking man's diet, but what we may need is the drinking man's Ralph Nader.

I believe in the political parties and in party loyalty. That's why I was disturbed by John Anderson's evasive answer to the question of whether he would support the Republican nominee. And that is why, as a Democrat, I want to heal the breach between Kennedy and Carter. If Jimmy Carter wants to stay president, he'd better care about it, too. Kennedy may be able to attract only a minority of votes, but his supporters represent a much larger portion of the Democratic Party's most active, committed members. If Carter doesn't make some gesture to win their support -- and fast -- he may suffer the fate of Hubert Humphrey, who lost the presidency in 1968 because he failed to bring the disaffected McCarthy supporters back into the campaign.

But I'm pessimistic that Carter will heed this lesson. Remember when, in the 1976 campaign, Humphrey withdrew from the race, Carter graciously commented that his only regret was being deprived of the opportunity to beat Humphrey in the next primary. There is nothing in the subsequent record to suggest that he or his chief aides -- Powell and Jordan -- have become more generously disposed toward their opponents.

Kennedy, I fear, will be equally unbending, but for reasons of ideology rather than of personal pettiness. He believes strongly that price controls and gas rationing are the best answer to inflation. So do I. But neither of us is president. Carter is, and he stubbornly continues to reject our program -- indeed, by failing to obtain standby authority to impose controls, he has virtually closed off that option, since any move to ask Congress for controls would itself send prices skyrocketing. Instead, Carter has chosen budget balancing as his way to fight inflation, and he's in command of the battle at least until Jan. 20. Should we continue to argue with him while inflation soars? Or should we try to make his program work -- by making sure, for example, that budget cuts are made in the right places?

Imagine yourself in an infantry battallion surrounded by enemy troops.

here are two points of attack offering the possibility of escape. One seems better to you, but your commander orders the other. Do you hang back and make the attack less effective? I guess I think not. The enemy is about to overwhelm us, and we've got to try to do something before Jan. 20.

My rim-riding friend recently tried to solve his problem by renting a car.

He asked for a compact. The clerk said, "Of course," and gave him the keys -- to a Firebird Trans-Am 6.6 with a 400-horsepower V-8 engine, quad-flared tailpipes, hood scoop, spoiler, mag wheels and a T-bar roof. It flew like a rocket, he reports, but only got 11 miles per gallon.

Here we have an insight into the facinating nomenclature of the rental-car industry. "Compact" means "Firebird." And "standard" may mean a giant top-of-the-line LTD with every accessory known to man -- but the rental receipt will simply say "Ford." That way the bookkeepers back at the home office never have to confront the profligacy of their expense-account executives.