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  3. 3. Your tires are your cars only connection to the road. Theyre overlooked as safety items,but sometimes theyre the first place where a problem will appear. We show you how toread your tires and know what the warning signs mean.Your tires are often the first indication that something is wrong with your car. The trick is readingthe signals.Lets start with the basics: Obviously you cant read the signals if you rarely inspect your tires. Sofirst, check the tire pressure at least once a month. Tires lose 1 psi each month under normaloperating conditions; buy an air compressor and get used to the idea of airing them up. Acompressor will pay for itself; fuel economy drops when tire pressure drops, and many gasstations now charge for air. Dont just look at the tire, feel it. Run your fingers along the tread, asmany irregularities are more easily felt than seen.Do your due diligence and you may detect a problem before the tire is ruined. And remember,your tires are your only connection to the road, and theyre one of the most overlooked safetyitems.What are your worn tires trying to tell you? Lets look at some weirdly worn rubber to find out.
  4. 4. Center WearIt Looks Like: Your tire is worn down only in the middle.The Diagnosis: This tire was overinflated, causing the center ring only to contact the road.Consequently, whoever drove this car had only a fraction of the rubber contacting the asphalt, sohis or her traction suffered.To find the correct tire pressure, check the door placard or the owners manual. Check thepressure when the tires are cold, before you start driving. Some people claim that you shouldoverinflate tires to reduce rolling resistance and increase fuel economy. But thats a fools game.You might save some fuel, but youll pay more in prematurely worn tires.If your pressure is correct but you still see center wear, this could indicate that the wheel andtires are not properly matched. There is one caveat here: Woody Rogers, product informationspecialist at Tire Rack, says that some rear-wheel-drive vehicles can produce center wear oncertain tires, even if theyre properly aired up and maintained. But thats true only for high-powered sports cars.
  5. 5. Cracking and BulgingIt Looks Like: Pretty self-explanatory.The Diagnosis: This usually comes from hitting a pothole, curb, or debris. Under inflation andover inflation put tires at a greater risk of damage from impacts.Large cracks in the sidewall that runs along the rim are either impact-related or caused bychronic under inflation. Numerous small cracks in the sidewall or tread blocks come fromexposure to the elements and age.Bulging is what looks like a pimple in the tire, most often in its sidewall. It happens when theresan impact that causes internal damage, but the damage doesnt show up until weeks or monthslater. With cracks or with bulging, youre looking at buying a replacement. "[The tire] should beremoved from service, regardless of the cost," Rogers says. "Eventually, it will fail."
  6. 6. Cupping (Also Called Scalloping)It Looks Like: A pattern of alternating hills and valleysThe Diagnosis: It happens when worn or damaged suspension components cause the tire tobounce as it travels, coming down harder on some spots of the tire than others. Bad shockabsorbers are the usual cause, though anything that connects the wheel to the rest of the car couldbe a culprit.Be careful with your diagnosis, though. Even tire shops sometimes incorrectly identify featheringor heel-toe wear as cupping. A wheel that is out of balance may also cause cupping or bald spotsto form, though there will be fewer hills and valleys than youd see with cupping caused by afailed shock absorber.
  7. 7. Diagonal SwipeIt Looks Like: Cupping or scuffing, but in a diagonal pattern.The Diagnosis: This tire trouble is most often seen on the rear tires of a front-wheel-drive carwith an incorrect toe setting. Insufficient tire rotation intervals may also cause a diagonal swipe.A third possibility: If you frequently carry heavy loads in the trunk or cargo area of a vehicle,that may change the geometry of the suspension, leading to a diagonal swipe.
  8. 8. Outer-Edge WearIt Looks Like: The inside and outside edges are worn down; the middle is not.The Diagnosis: This is a telltale sign of under inflation. Too little pressure is arguably the mostdangerous condition for a tire, as it will flex more and the heat that builds up could cause ablowout. (Remember the Ford Explorer Firestone mess? The cause was mainly underinflatedtires.) And an underinflated tire wont absorb bumps well and may knock the front end out ofalignment or damage the suspension.How to Avoid Under inflation: Again, keep an eye on your tire pressure by checking it monthly.Dont rely on the cars tire-pressure monitoring system to let you know when a tire is low on air."[The warning systems] threshold is typically 25 percent underinflated," Rogers says. Thismeans a tire that should be at 28 psi could be down 22 psi before you see a warning light. Andthat could be low enough for you to destroy a tire.
  9. 9. FeatheringIt Looks Like: Feathered tread blocks are shaped like a series of ramps in a directional wearpattern that goes sideways across the tire. The lower edges of the ramps are rounded while thehigher edges are sharp. If you cant tell by looking, run your hands across the tread blocks.The Diagnosis: Most often, feathering means the cars toe setting (a measure of the carsalignment) is off. If the toe setting is correct, a worn or damaged suspension bushing could becausing the cars alignment to shift as you drive. Check for worn or damaged ball joints andwheel bearings as well.
  10. 10. Flat SpotsIt Looks Like: One single spot on the tire is more worn down than the rest.The Diagnosis: Single spots of heavy wear show up on the tires when a car has been in a skid—say, the driver saw a deer on the highway and slammed on the brakes. A car without an antilockbraking system is more likely to lock up its tires under heavy braking, which can cause a flatspot.Also, cars that are parked for extended periods of time risk getting flat spots where the weight ofthe car has deformed the patch of tire contacting the ground. Unlike flat spots resulting from askid, these show no additional tread wear—but nonetheless, the tire is misshapen. Althoughradial tires can have this problem, bias-ply tires are more prone to getting flat spots from sittingtoo long, especially if the tires are sitting in any kind of corrosive liquid, such as gasoline orantifreeze.
  11. 11. Heel-ToeIt Looks Like: Feathering, only the ramps run front-to-back along the tire rather than side-to-side.The leading edge of the tread blocks will be worn smooth while the trailing edge will be sharp.The Diagnosis: "[Its] definitely one of the most common conditions we see," Rogers says."Because its so common, a lot of people think its normal." Heel-toe wear is typically a symptomof insufficient tire rotation intervals. So check your cars maintenance schedule and make sureyou keep up. Misalignment or worn or damaged suspension bushings, ball joints, and wheelbearings can also cause heel-toe wear.
  12. 12. Single-Side WearIt Looks Like: One side of your tires wears down faster than the other.The Diagnosis: The cars camber setting is likely off, causing the tire to lean too far to one side.Take the car for an alignment adjustment. Worn or damaged springs, ball joints, and suspensionbushings can also cause single-side wear as could carrying heavy loads frequently, incorrect toesetting, and insufficient tire-rotation intervals. Some performance cars leave the factory withenough camber to induce single-side wear, but thats rare.
  13. 13. Tread-Wear IndicatorsThey Look Like: Ridges between the tread blocks. They sit tucked away between the treadswhere they cant contact the road.The Diagnosis: When the tread wears down to the point that it is flush with the indicators, the tirehas reached the end of its life. But depending upon the driving conditions you usually encounter,you may not want to wait for the indicators to become flush with the tread.The tread depth of a typical tire is 11/32 inch, and those channels are there to funnel out waterand prevent hydroplaning. The tread-wear indicators are 2/32 inch high, but Rogers recommendsno less than 5/32 to 6/32 inch of tread for snow and 4/32 inch of tread for rain or sleet. Wet-weather performance declines significantly after 4/32 inch, so replace the tire before itsindicators become flush with the tread block.