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What Women Need to Know About Tires
(Comment #3: May 29, 1999)

   I wrote this article especially for women. I know...that may not be politically correct these days; but tough! The image of my mother, my daughters, or any woman having car trouble and being stranded is hateful to me. Heck! The image of my being stranded is hateful to me! Anyway, I know that almost no women who read this will pay attention to my comments. Why should they if they have a man available to do things for them? But if only one woman ever needs this information and recalls it I'll be repaid for writing it. Hey!...

Here's What You Need to Know
About Tires and Wheels
   In order of importance to you they are:
  • How to maintain your tires
  • How to change a flat tire
  • How to rotate your tires
  • How to inspect your tires
  • How to buy new tires
  • How to fix a flat tire

women can fix cars
Zack Hinckley is an instructor at Kennedy Space Center
How to Maintain Your Tires An easy way to avoid tire problems is preventive tire maintenance; and the most important maintenance you can perform on your tires is keeping them properly inflated. Underinflation causes lost gas mileage, lost tire mileage, unsafe handling, and greater driving noise.
   The recommended maximum inflation pressure is molded into the sidewalls of most tires—it may also be on a placard on your driver side door post—generally about 35 to 36 psi (pounds per square inch). Any less than this pressure and your tire is performing inefficiently. It is safe to keep all your tires inflated to this indicated pressure, or even slightly above.
   The easiest way to properly inflate your tires is to go to a service station that offers tire inflation and ask to be sure the air compressor is working. When you are sure it is, select the inflation pressure on the pump indicator. Remove the valve cap from your tire and press the tiny stem in the valve; release air for about three to five seconds. Now, press the pump's air chuck tightly against your tire valve and the pump will begin to inflate the tire.
   Automatic air pumps usually sound a periodic bell as the tire is filling. When the tire is full the pump stops and the bell stops ringing. For accurate filling, the pump should operate long enough for the bell to ring at least three times before the pump stops. If it stops before six rings, let some more air out of the tire and inflate it again. Use this simple procedure to make sure all of your tires are inflated the same amount.
   When you finish with your tires, check your spare. You should inflate it 10 or so psi MORE than the tires on the ground; that way your spare will always have enough pressure for safe use. The special tiny spares supplied on many modern cars require a special high pressure; check the requirement on the side of the tire or in your owner's manual. Write it down or mark it on the spare with yellow crayon.
   Finally, put all the valve stem caps back on the tires and return the air pump hose to its hanger on the pump.

Tire Inflation
tire gauges
Electronic, mechanical tire gauges
How to Change A Flat Tire

commercial chocks
commercial tire chocks
This is not fun, but it is not hard. It is wise to practice this at home, in good weather, a couple of times. You'll get very confident and efficient with only a little practice.
   First, be sure your car has:
  • a spare tire;
  • a jack and a jack handle;
  • a lug wrench;
  • a hubcap removal tool;
  • a block of wood about 4 x 4 x 12 inches long, or a special tire chock, available at low cost from most auto parts stores.
If you don't have these things, you should get them; they are all necessary. In many cars the lug wrench and hubcap removal tool is part of the jack handle, but it may be a separate wrench.
   Locate the jack attachment point on the car. Bumper jacks usually have a hook which fits into a slot on the face of the front or rear bumpers. Body jacks usually have a post or a lug or a hook that fits into a special location along the bottom sides of the car beneath the doors. Check your owner's manual for these locations and then be sure you can find them. They are the only safe lifting locations on the car. When you know where to attach the jack, remove it and the spare tire from their storage positions.
   Be sure you know how to use the jack. Some jacks use a pumping action on the handle and an up/down selector lever to ratchet the jack up and down. Some use a cranking action on a screw. Read your owner's manual. Place the jack under the correct support point and lift the jack until it just engages the lift point. Now place your tire chock (that piece of wood) under the downhill side of the car's rear wheel on the side of the car which will not be lifted. This is to prevent the car from rolling and falling off the jack. When the tire is chocked, jack the car up an inch or two; stop a little before the tire leaves the ground.
   If your wheel has a hub cap now's the time to remove it. Some hub caps can be pried off simply with the wedge-shaped end of the jack handle; some have small holes for removal with a special tool supplied with the car; some twist off. Read your owner's manual! If your car has custom decorative hubcaps, they may be locked in place with a special hub cap lock. Be sure to unlock them before you try to pry them off; and pry very carefully at several places around the rim to prevent damage. Return your hub cap key to the glove compartment after you use it. If you lose that key you will have a great deal of trouble trying to change future flats.

wooden chocks
homebuilt tire chocks
always pull
Pull to loosen...
   Use the lug wrench to loosen the nuts on the wheel about 1/4-turn. Loosening the nuts with the wheel still touching the ground is easier and safer than when the car is fully lifted. The weight of the car is still partially on the wheel at this point, so just barely loosen the nuts. Remember, nuts loosen in a counter-clockwise direction UNLESS the lug has an "L" marked on it, in which case it loosens clockwise.

Safety hint:
when loosening lug nuts, position the wrench so you pull it to loosen the nuts! Avoid pushing a wrench.

odd pattern
loosen/tighten in odd pattern
   Finish jacking the car until the wheel is completely clear of the ground. Loosen all the nuts before taking any of them off. If there is an odd number of nuts (usually five) loosen alternate nuts until all are loose. If there is an even number of nuts (usually four) loosen opposite nuts until all are loose. If there is a hub cap lock spider on the wheel, take a close look at how it's installed, so you'll be able to put it back on the same way. Finally, remove the nuts, starting at the top of the wheel and saving the bottom nut until last. Put the nuts in the hubcap for safe keeping.
   Remove the wheel and replace it with your spare. Replace the lock spider (if there is one) and all of the lug nuts and screw them on finger tight. Bump the side of the tire with the heel of your hand as you tighten the nuts to be sure it is installed flat against the axle hub. The cone-shaped nuts should fully bottom in their holes in the wheel and the spider should be slightly loose. When all the nuts are in place, tighten them very snug with the lug wrench and bump the tire again several times to be sure it is securely installed.
even pattern
loosen/tighten in even pattern
   Now, lower the car with the jack until the wheel is touching the ground. Use the lug wrench to securely tighten the nuts. They should be firmly tightened, but not so tight that you have strain to tighten them. Lower the jack fully and remove it.

Safety hint:
when tightening lug nuts, position the wrench so you pull it to tighten the nuts! Avoid pushing a wrench.
pull to tighten
...pull to tighten
   Replace the hub cap, making sure you carefully align the tire valve with its hole in the hub cap. The tire valve should be free to move within the hole—it should not bind against one side of the hole. Tap the hub cap in place evenly with the heel of your hand.
   Finally, restow the jack and the rest of the tools, remove and store the chock from the wheel, and place the flat tire in the trunk. Don't attempt to remove any foreign object from the tire—leave it in place to mark the puncture location when the tire is to be fixed. Don't forget to have the flat fixed or fix it yourself as soon as possible (today!)
   Hey! There are a lot of small variation in things like lug nuts, hub caps, lock spiders. Before you remove anything, take a close look at it and be sure you remember how it's oriented.

How to Rotate Your Tires In general, two of the tires on your car drive the car and the other two simply roll and bear weight. Older cars use the rear tires for driving and the front for steering. Newer cars use the front tires for driving and steering. In either case, the driving tires wear faster than the passive tires. If you periodically change the front tires for the back tires the whole set will last a little longer. Also, this changing, or rotation, allows you to check the tires for early signs of defects. Rotation is especially important if you own an imported car with relatively small tires (13-inch or less.) They wear much faster and less evenly than larger tires.
women can rotate tires
Four tire rotation
   The simplest rotation pattern involves only the four tires on the ground. If your car uses one of those tiny spares, this is the method you'll use. Swap the rear left with the front left, and the rear right with the front right. Leave the spare in the trunk. This pattern has the advantage of always allowing the tires to roll in the same direction, no matter whether on front or rear, and it reserves the spare in best condition for emergencies.
   Another rotation pattern involves all five tires. You cannot use this method if your car uses one of the special, tiny spares. Swap:
  • spare to left rear
  • left rear to right front
  • right front to left front
  • left front to right rear
  • right rear to spare
In this pattern all the tires change rolling direction between rotations, and the spare is used the same amount as all the other tires.
women can fix flats
Five tire rotation
   You should rotate your tires once every 5000 miles (OK, OK...every 10000 miles), using the same removal/replacement procedure you used, above, in changing flat tires. Regular tire rotation can increase the life of your tires 30% or more; and as you rotate them, you'll have the chance to inspect each tire closely. You can't make this sort of inspection with the tires on the ground.

How to Inspect Your Tires If you're going to maintain your tires preventively, you're going to have to keep an eye on their condition. That means periodic tire inspection. You can do simple inspections occasionally by just looking at them as you move around your car. The best time for a good look, though, is while you are rotating your tires. Some of the things you'll see are normal, some are not. Normal conditions:
  • inside edges of all tires worn more or less than outside edges
  • small rocks wedged in tire tread grooves
  • minor scratches or cuts in sidewalls of tires
  • small cracks in the sidewall rubber.
Abnormal conditions:
  • inside or outside edges of one or both front tires worn noticeably more than those of rear. (Wheel alignment is wrong. Get it fixed, and then have the tire(s) balanced.)
  • metal objects, glass, or thorns stuck into tread or sidewalls. (Don't remove the object! See notes for fixing a flat, below.)
  • flat spots, cups, or bands worn into edges or tread of tires. (Bad shock absorbers, tire out of balance, defective tire to begin with. Start saving for new shocks or tire.)
  • cuts in sidewalls deep enough to expose fabric of tire, OR
  • tread grooves worn to less than a penny's thickness, OR
  • tires worn so thin in spots that metal or cloth fabric shows through rubber. (Get a new tire without delay!)
   If your inspection shows the normal conditions noted above, everything is probably OK. Complete your rotation and inspection and reinflate all the tires as a final step.
   If you observe any of the abnormal conditions above, you should take corrective action immediately. Don't wait even a day, or you may be stranded.

How to Buy New Tires The goal in buying new tires is to get good new tires at the lowest price you can.
   There are many good brands of tire available on sale. Check your local papers for tire sales and compare prices widely. Always get exact tire size matches, and do your best to get exact brand and model matches for your old tires; but don't be surprised if this is not possible. When you find prices you like, ask the dealer to show you which of the tires of the correct size are most like the tires you will be replacing. Be sure to ask if the tires include a guarantee. If they don't, don't get excited, especially if you've got a good price quote. If they are guaranteed, ask the dealer to explain the guarantee.
   Always replace single worn tires with new tires of the same type—radials for radials and bias-ply for bias-ply. Never mix radials and bias-ply tires in a set—that can cause dangerous handling problems on rough or wet roads. If you are replacing a complete set of worn bias-ply tires, get a new set of radials.
   If you have been rotating your tires in the four tire pattern, and your spare is a full-size spare, put your spare on the ground and use the best of the old tires as your spare. Now you'll have to buy only three new tires at this time. If you've been using the five tire pattern, keep the best tire for your spare and buy four for the ground. Always put your best tires on the ground, and the very best on the driving wheels.
   Always have new tires spin-balanced when you buy them, and tell your dealer not to replace the old valve stems unless they are physically damaged (that's a needless expense.) After the transaction write the mileage on your receipt and keep it for use in case of a claim against the guarantee, and to track your tire life.
   In my experience one brand of tire has been consistently very poor, with dealers who range from discourteous to downright dishonest. It would be impolite to tell you the name of the company, but I recommend you avoid any tires whose name begins with "Goody".
   Notice that this discussion has mentioned only new tires. Never buy recapped tires for any reason. They fail quickly, and they are not cheap enough to be worth the safety risk. The pieces of tire you see along interstate highways are almost all from recaps, and are a good indication that they are not roadworthy.

How to Fix a Flat Tire If you notice one of your tires has begun to look flatter than the others, you may have the beginning of a flat. The easiest way to fix a flat is to have someone else do it. I highly recommend this method; it should cost only about $5.00 per tire. If you understand the process and have the tools, you can do it yourself and save a dollar or two.
   Repairing a modern tubeless tire is simple. Start by buying a tubeless tire repair kit and reading the instructions. A simple kit for repairing tubeless tires is available for less than $5.00 from most discount stores or auto parts stores. It contains rubber cement, enough hole plugs (heavy tar-coated string) to repair about a dozen tires, and an insertion tool. To use the kit:
  • locate the puncture and mark it with yellow crayon;
  • remove the object that caused the flat;
  • coat a plug with rubber cement and insert it into the hole;
  • cut off the plug and reinflate the tire;
  • test it to be sure the leak is fixed.
   The details that follow outline the method of repairing a flat when the hole or damage is in the tread of the tire. If it is in the tire sidewall, this method doesn't work; in fact, almost NO method for repairing damage to the sidewall is reliable. The sidewalls flex too much in use to retain the repair. Get a new tire. For tread damage, read on.

The details:
1. During your tire inspection, if you notice a nail, wire, or thorn imbedded in the tread of your tire, do not remove the object, but do replace the tire with your spare.

2. With the punctured tire off the car, clearly mark the location of the object with a grease pencil or crayon; then remove the object. If you do not hear air escaping (assuming the tire has not gone completely flat), coat the hole location with saliva or soapy water and look for bubbles. If you see no bubbles after about 30 seconds, this isn't the location of the damage. Keep looking. If you hear air escaping or if you see bubbles, you'll need to fix the flat.

3. Separate one of the tarry string segments from the repair kit and thread it through the hole in the end of the insertion tool. Coat the string and the shaft of the insertion tool liberally with rubber cement and rub cement on the hole in the tire. Now, very forcibly insert the tool, with the string, straight into the hole all the way to the handle of the tool. Twist the tool until the string is drawn completely inside the tire. Finally, withdraw the tool carefully, twisting as you pull, until the tool and about one inch of string is pulled back out of the hole. Clip off the string close to the tread, and the flat is fixed. Clean the insertion tool thoroughly and pack the kit away in a cool place for (perish the thought) later use.

4. Reinflate the tire to spare pressure and check it for leaks with saliva or soapy water. If no bubbles appear after 30 seconds, the tire is probably OK. Check it over one more time just to be sure there isn't another damaged spot. When you're sure there are no more leaks, return it to your trunk and bask in a sense of great accomplishment.


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