Watch out for dented or chipped wheel rims. A wheel's rim needs to be perfectly round; if it's not, the chance of tire failure is greatly increased. Wheels made from steel can be straightened fairly easily by a tire shop, but aluminum wheels are tougher to repair. Don't try to do it yourself.

Any vehicle's handling will be affected if you use different brands and models of tires. It's especially bad to have two different tires on the front of a front-wheel drive vehicle.

Tire repair aerosol cans are cheap and widely available. They work by injecting a chemical substance into the tire as they inflate it. Note: This liquid that flows into the tread puncture and fills the hole is a temporary solution so you can get home. If it works on your flat tire, don't imagine that you've solved the problem permanently. Take the tire to a shop and have them put a plug into the tread, and put a patch on the inside of the tire. If the damage to the tire is too serious to repair, you'll need a new tire.

When you buy a new tire, the dealer will want to charge you for a new valve stem, "unless you want to try and reuse the old one." Smile and nod, and pay for a new stem--you're better off spending a little extra cash now, and saving yourself a big headache later (when the old valve gives out).

2torial #0518: Learn2 Understand Tire Care (Continued) Do your own maintenance Tires don't require a lot of everyday maintenance. The two main strategies are to keep them inflated to the proper pressure, and to protect from the elements. They'll last longer, ride better, and be less likely to blow out. Tire pressure: The trickiest part of checking your tire pressure is that you actually have to check it twice: once before the vehicle has been moved that day, and again when you're at a gas station with an air hose. The first reading is from a cold tire, and it's the accurate one, while the second is from a tire that has warmed up from rolling on the pavement. The second reading will be a bit higher than the first. Here's the routine: Get a good quality tire gauge, and measure the pressure in all four tires before you move the vehicle. You'll do this by removing the plastic caps on your valve stems (see Keywords) and pressing the gauge firmly down over the metal threads on the end of the stem. You'll hear a little hiss as a bit of air escapes, but when you press the gauge firmly down and hold it there, the noise will stop and the gauge will register the tire pressure.   Write down the measurement for each tire--this is your cold measurement. Tire companies specifications reflect cold tire pressures, and pressure is measured in PSI, or Pounds per Square Inch.   The auto manufacturer has specified tire pressures for both front and back tires. Look for these specs on the inside edge of the driver's door, on the inside of the glove compartment door, or in the owner's manual. Use these numbers, rather than the numbers printed on the outside of the tire, to find out how much pressure should be in the tires.   Compare the cold measurements with the manufacturer's pressure recommendations. If the manufacturer recommends a different pressure (either higher or lower) than the cold measurement, you'll adjust the tire pressure accordingly.   Find a service station with an air hose. Sometimes you'll need to put a coin in to make it work, but in most places there won't be any charge. There will either be a metal handle that releases air when you squeeze it, or a simple metal fitting that releases air when it's pressed over the valve stem.   Take the tire pressure again with your own tire gauge. It'll probably be a bit higher than the cold measurement, since the tire has warmed up from rolling along the pavement. This will be the warm measurement.   If the cold measurement was lower than the manufacturer's recommendation, add the proper amount of air with the hose. How much? Use the warm measurement as your guide. Let's say you compare the cold measurement (say, 32 PSI) with the manufacturer's recommendation (35 PSI)--the tire needs three more pounds of pressure. If the warm measurement was 34 PSI, fill up the tire until the gauge reads 37 PSI. Don't worry if the final measurement is more than the manufacturer's recommendation--tomorrow morning, when the tire is cold again, the pressure will be correct.   On the other hand, if the cold measurement was higher than the manufacturer's recommendation, release the excess pressure from the tire. (This is easy to do: find the valve, and press on the metal piece in the center of the valve with your fingernail, a key, or a small stone, until your hear a hissing sound.) Again, use the warm measurement as your guide. For example, if you knew from your cold measurement that the tire had two pounds of excess pressure, and the warm measurement is 38 PSI, release pressure until the gauge reads 36 PSI.   Tires lose pressure at different rates. If you measure tire pressure every few weeks or so, you'll get a better idea of how often adjustments are necessary. Don't try to go by the tires appearance, as modern radial tires often look under inflated when they're not.   Overly inflated tires can wear unevenly, so don't try to overinflate them into balloons. Tire protection: The tire's rubber compounds can dry out and crack just from daily exposure to sun, water and road salt. There are quite a few pump-spray rubber and vinyl dressings on the market now, and they work well on tires. Some of them are even marketed specifically for tire care.   Buy any one of the pump sprays which says that it protects rubber against UV exposure and follow the directions in applying it. Use it on the side of the tire, not the tread. If you apply the stuff three or four times a year, chances are that you won't wind up lots of little cracks in the side of the tire, and the tire will have a better shot at reaching a ripe, old age on your vehicle. -end- Learn More! or All steps at once (printable version)