– DEAR TOM AND RAY: My boss and I are in a never-ending prank war. I really want to hook up one of those horns to his car that plays the ice-cream-truck jingle. And I want to have it come on whenever he starts the car. The problem is that I have no idea how to do this. Can you guys help me? Cheers! — SaraMarie

RAY: That’s a great prank, SaraMarie.

TOM: That meets all of the criteria of the American Prank Association: Nobody gets hurt, physically or psychologically. It’s reversible, so there’s no permanent damage to person or property. And, most importantly, it’s not mean-spirited, so the prankee can laugh along and appreciate the cleverness that went into pulling it off — while he’s plotting his revenge.

RAY: So we approve of this prank wholeheartedly. The first thing you’re going to have to do is find the horn. I don’t know where you get a horn that plays “Turkey in the Straw” (the annoying musical dirge of choice for ice-cream trucks), but I’m sure someone out there makes one.

TOM: I don’t know where you’ll find it, but I’d say the prospects are good. After all, we’ve heard horns that play “La Cucaracha,” “Dixie,” the cavalry call, the theme from “The Godfather” and the mating calls of a wide variety of farm animals. So check online, or try the JC Whitney catalog.

RAY: Then you’ll need to recruit a mechanic who’s willing to play along. I suggest a guy who can run fast if he happens to get caught in flagrante delicto — which is Latin for “with battery cable in hand.”

TOM: But you’re going to prevent that from ever happening. Since you work with your boss, you’re going to schedule an important meeting for him — preferably in a windowless room — while the mechanic is working on his car in the office parking lot. And you are going to keep him there until you get word that the coast is clear.

RAY: Installing a horn is a pretty easy job. Your mechanic shouldn’t even need the keys. He’ll just need a wiring diagram, so you’ll have to provide him with the year, make and model of the car. The trickiest part is getting the hood open without having access to the passenger compartment. But we often manage to do that from under the car when people’s hood latches break.

TOM: Once the hood’s open, it’s a simple matter of hooking up the horn and connecting the control box to any wire that gets energized when the ignition is on. So whenever he turns the key, the control box is powered. And if the horn is turned on at the control box (which is how you’ll leave it), kids from miles around will descend on him demanding their creamsicles.

RAY: Then all the mechanic has to do is hide the control box under the hood somewhere. You don’t want to make it too easy to find, but you want him to eventually be able to turn it off — don’t you?

TOM: You don’t? I’m glad you don’t work for me, SaraMarie! Well, let us know how it goes. And we’ll start thinking about revenge ideas for when your boss writes to us. Have fun.

DEAR TOM AND RAY: I’m writing for my brother, who never reads your column. He has a 2010 Toyota Prius with all the bells and whistles. He was told that to get the best gas mileage, he should buy low-rolling resistance tires. His dealer has never heard of them. What are they, and how do they increase gas mileage? — A loving sister who reads you guys a LOT, Margaret

RAY: Well, we’re sure Mom always liked you better anyway, Margaret.

TOM: Your brother already has low-rolling resistance tires, Margaret. They come standard on every Prius.

RAY: I certainly can understand that he might not be aware of that. What I don’t understand is why the dealer doesn’t know about it — unless he has a low-rolling attention span.

TOM: Here’s the story on low-rolling resistance tires. Everybody’s always looking for ways to increase gas mileage, right? One thing that decreases mileage is friction. As tires roll along the ground, they create what? Friction!

RAY: So the thinking goes, if tires could roll more easily, there would be less friction — or rolling resistance — slowing down the car, and the car’s mileage would improve.

TOM: And lo and behold, this works! Tire manufacturers came up with new rubber compounds that allow cars to roll more freely while still maintaining a grip on the road. They’re not designed for high-performance sports cars, but they function perfectly well for most people.

RAY: A person who buys a Prius is not going to drive it at high speeds around hairpin turns in the rain. Prius owners prioritize mileage over sports-car handling, so Toyota opted for a tire that maximizes what the buyers care most about.

TOM: Similarly, if you buy a Porsche, it’s not going to come with no stinkin’ low-rolling resistance tires. Because if you ask the average Goldman Sachs partner why he bought his 911 Targa 4S, the answer is not going to be “For the mileage.”

RAY: But low-rolling resistance tires are available for non-hybrids now, too. And for people who don’t need extraordinary handling qualities from their tires, they’re a good way to boost your mileage by a few percent.

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