The rear tires on my car are cupping, which never happened before. The dealer set things right to specs and rotated the rear tires to the front. The mechanic said he hoped they will "wear in." He said all it takes is one good pothole to cause the rear tires to cup. Now the back tires are slowly cupping and the fronts are becoming louder and louder. What is going on?
A I wish you had included the year, make and model of your vehicle. I'm going to assume it's a front-wheel drive automobile -- unusual rear tire wear is more common on a FWD vehicle.
The most common cause is failure to rotate the tires every 6,000 to 8,000 miles. Because there is less weight over the rear axle, the springs and shock absorbers/struts tend to be a bit softer. As the shocks wear, they can allow more up/down oscillation, which can initiate the cupping or unusual wear.
Obviously, lower quality or poorly balanced tires can develop unusual wear prematurely. Remember: Tires are the most important components on your vehicle and, as the saying goes, you get what you pay for.
Sadly, once an unusual wear pattern develops on a tire, it will not "wear in." If the tires still have well over half their tread remaining, you could try having the tires shaved or "buffed" on a special machine that shaves off the cupping, leaving a like-new remaining tread surface. The cost of this compared to quality new tires usually makes the new tire choice more logical.
Q This is not a repair question. If I remember correctly, you used to race cars. My question is this: When I've watched Formula I, the driver has his arms fully extended, yet NASCAR drivers have the steering wheel close to them. Why the difference?
A Fun question, and as an instructor I still spend time driving the Skip Barber Mazdaspeed MX-5 race cars. NASCAR drivers sitting up close to the steering wheel has its origins in the early stock cars, which had no power steering and slow ratio steering boxes. Add to that the characteristics of NASCAR oval racetracks -- long duration corners where the driver has to hold the steering wheel in a turned position and make subtle and delicate corrections to keep the car under control. Sitting close to the wheel with a significant bend to the arms increases leverage and finesse. Even though today's "stock" cars are pure race cars with power steering, drivers still sit relatively close to the steering wheel for comfort and control.
While it seems that open wheel racers -- Formula 1, IndyCar, etc. -- sit with their arms fully extended, that's not as true today as it was years ago. Though they might not need as much muscle on the steering wheel, they still need that delicate touch and control. Over the years it seems that these racers are, in fact, positioned closer to the steering wheel than in past years.
Two things to remember: The closer you sit to the steering wheel the less physical effort is required and the farther you can turn it without having to reposition your hands. With your hands at roughly the "10 and 2" position and a reasonable bend at the elbows, you can turn the steering wheel more than 180 degrees without having to "shuffle" your hand position.
It's worth remembering for street driving as well.
Q I have 2004 Ford Focus. When placed in gear, the car will not move, but there is a ratcheting noise coming from the transmission area. The axles show no damage. Does the transmission have something broken inside?
A Quite possibly, but make sure that one of the front axle/driveshafts hasn't been pulled outboard enough to disengage the drive splines on the inner end of the inner constant velocity (CV) joint. If this happens, the car won't move.