Q: My 2003 Volkswagen Passat calls for tires with an H speed rating. For replacements I'm getting conflicting advice. I'm told dropping to an S rating will save me money, provide a quieter and smoother ride and yield longer tread life. The other view is handling and braking will suffer. For a nonaggressive driver in a nonperformance vehicle, can you help sort out how much better the handling and braking really are?—Raf Frankel, Sanibel, Fla.
A: Speed-rating charts for tires might get more laughs than the average party joke because of the overkill they reflect. How many people drive pickup trucks and minivans at 150 mph, after all? In your case the H rating means you can safely drive your wagon at 130 mph. Moving to an S-rated tire drops the top speed to 112 mph, which probably still gives you enough of a safety cushion. While it is true that higher-rated tires typically help vehicles turn and stop more effectively, the difference may not be worth the added cost and hassle of replacing pricier tires more often.
Q: My 2004 Audi A4 V6 has 90,000 miles. It was recommended to change the timing belt at 75,000 miles. I have not done that yet. It is very expensive to replace this belt. Do you think this is a necessary repair since my car is handling and sounding fine?—Howard Keys, Traverse City, Mich.
A: People familiar with Audi and its history of timing-belt trouble would say you are living on the final minutes of borrowed time.
A few years ago the car maker settled a class-action lawsuit about belt problems on A4s slightly older than yours, but some people believe the belt systems may be fragile on later cars as well. You should call your mechanic.
Q: When I take my 2007 Toyota Solara convertible to the carwash, the owner always recommends waxing it two to three times a year, which I have never done. What are your recommendations on car waxing?—Molly Alger, Westport, Conn.
A: Waxing is a good practice in part because it forces drivers to wash their cars. It also protects your paint and keeps the car looking better longer. I think two to three times a year is generous and once a year is still pretty good.
Q: I own a 2007 Mercedes C280 4MATIC and just took it for a 75,000-mile service. I asked about tire rotation and was told by the mechanic that four-wheel-drive cars don't need tire rotation. Upon inspection the right rear tire has significant wear compared with the others. Should I just demand the rotation of a least the two rear tires?—Peter Prest, Marble Cliff, Ohio
A: The rule of thumb on all-wheel-drive cars is to rotate the rear tires to the same side on the front and move the front tires to the opposite side in the back.
Follow directions for your specific tires, as asymmetric or unidirectional tread designs, or front and rear tires that are different sizes, can limit your rotation options.—Email email@example.com