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Q: A modified pickup truck — loud muffler, high off the ground and very wide tires (at least 3 to 4 inches beyond the fender) — passed me going very fast. I didn't mind the speed; it was the piece of junk that the right rear tire kicked back. It went over me and hit the car behind me, cracked the windshield and nearly caused a catastrophic accident. Aren't tires supposed to be covered by extending the fender to prevent incidents like this?
A: In many states, but not all, tires that extend beyond the fenders are illegal. That is because incidents such as yours are a true safety hazard. In Minnesota, the law says that "wheel flaps or other suitable protection ... must be at least as wide as the tires they are protecting."

Size matters

Q: I owned a 2008 BMW Z4 and could not rotate the tires front to back because the back tires were wider than the front tires. I'd double check your advice about tire rotation.
A: My answer was for general tire rotations. There are exceptions, as you pointed out, but I try to aid the largest portion of my readership. Yes, different sized tires cannot be moved to another axle. Tires with a specified direction of rotation don't follow the general rules, either. In this particular case, I blew it by overlooking the reader's mention that it was a BMW Z4.

Wild wipers

Q: I have a 2012 Chrysler 200 and have a problem with the wipers turning on with the wiper switch off. When that happens, I have to turn the switch on and then off for them to stop. I took my car to the dealer and they couldn't get it to do it, but they looked in Chrysler's archives and found that a ground wire could be the problem. They cleaned all of the ground wires, but the problem continues. Any suggestions?
A: There are not many ground wires in a car. In fact, almost the entire car is the ground circuit. And here's the weird part of that: A poor ground on another component could be causing a ground somewhere else, and that somewhere else might be your wiper switch.

Giving it the boot

Q: While having my 2013 Chevy Malibu checked out before making a six-hour drive, it was discovered that I needed an axle boot replaced. Was there a possibility of anything going bad for me if I had been unaware of the boot issue?
A: If the tear is recent, you would have been fine. The boot covers the constant velocity (CV) joint on the axle, and the grease does not usually spew out quickly. If you wait too long, dirt and grit can enter and damage the CV joint.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to motormouth.tribune@gmail.com.