Tuesday, December 1, 2009

Changing a Car Tire - Part 1

It was late in the afternoon on Thanksgiving Thursday, and I get a phone call. "I'll be a little late, I have a flat tire" I hear the voice of my cousin say on the other end of the line. This last week as I was swapping out winter tires (no I did not get Trax for my car), it occurred to me that the simple task of changing out a tire is not always so simple, and to some daunting and impossible. The most common responds I hear from people that do not know how to change a tire is: that is what cell phones and AAA is for. Cell phones don't always work, and it can take up to two hours for a AAA service call to finally reach you. Having a flat tire and not being able to change it out is like shitting your pants cause your shoelaces were not tied and therefor you couldn't walk to the bathroom. Ridiculous; exactly.

I figure I would layout some tire changing tips. With the proper technique anyone can do it; it does not matter how strong you are. I will break up this into two parts. Part one is how to change a flat tire on the roadside. Step two is how to change your tires quickly in the garage. This second part especially pertains to changing out all four tires or rotating your tires.
Preparation-At some point you should make sure you have everything needed to change out a flat tire stored in you car. Only three basic items are needed: jack, lug wrench, and a spare tire. When checking you should make sure that the spare is inflated properly. Other items that you might need are hub cap removal tool, lock lug nut "keys", wheel chocks, hazard single (flares or reflective triangles).

Lug Nut Removal-This should be the first step. With the vehicle parked on a level surface, the lug nuts should be "broken" when the car is still on the ground. Broken refers to loosening the nut but not removed. It is much safer to do so with the car on the ground as oppose to being in the air. Things that might cause difficulty: Hub caps. Some wheels have a hub cap that need to be removed before you can access the lug nuts. Don't be fooled by the fake lug nuts on the hub cap. Most caps can be pried off, some require a key or a hex tool to remove (take care of this in the prep). Some lug nuts are keyed for security reasons. Make sure to have the key. Finally lug nuts might be torque enough that will make it difficult to remove. A LN is suppose to be torqued to less that 100 ft/lbs. A stock lug wrench is typically more than a foot long, and the average human is more than 100 pounds. Thus if you stand on the end of the wrench you can most likely break it free. Remember to make sure the wrench is properly seated on the nut. Really it is so easy even a kid can do it, though the wrench handle should be on the left side of the nut for removal, the kid in the picture surely is tightening the nut.




Jacking-The next step is jacking up the car. Each manufacture supplies their cars with their own jack and jacking location. Part of the prep work is to know where on the car to jack. These locations are different between makes and models. Most cars seem to jack on the pinch weld at a location designated by a notch. German cars often have a jacking port, and solid rear axle trucks typically jack on the axle itself in the rear. Prior to jacking make sure the car is parked on a level surface, and set the parking break. For added security, place a wheel chock or large rock/piece of wood against the wheel opposite the corner being jacked up.

Lug Nuts-Now that the flat tire is in the air, and the lug nuts are loose, the next step is to remove the lug nuts and then the wheel. The term lug nut is generic. Some cars (Audi's) have lug bolts. Their function is the same. The thing to remember is not to lose any. Lug nuts/bolts are very easy to lose working on the side of the road in the dark.

Removing Wheels- Most of the time the wheels just come off. However sometimes a wheel could be stuck. Some wheels are known as hubcentrics, meaning that the wheel rest on the hub and sometimes they are stuck on. A good jerk will often times free the wheel from the hub. Sometimes however not. A whack with a large sledge hammer will almost always work. But often you do not have a hammer when stuck with a flat on the side of the road. A kick with the heel of your foot is the final option. Be aware that kicking the tire could cause the car to fall off it's jack. Locate your body so that the car will not crush you when it falls, and block off extra wheels and tires for added security. You can even place large solid objects under the car which are larger than you so that the object takes the weight of the fallen car.

Installing Wheels- This could be the hardest part of the job. Wheels and tires are heavy. Roll the wheel in place. Line up the studs with the holes in the wheels, this is the most important part. Rotate the wheel so the holes are properly orientated. I use two different lifting techniques. One is to put your leg against the tire. Hold the top of the tire and lift and roll the tire onto your leg then slide back onto the studs. The other way is the squat in front of the wheel. Grab the lower portion of the wheel and rest your forearms on the inside of your knees and shin. Using your calf muscle lift the heel of your foot of the ground, your forearms and the wheel. Line up the holes on the wheel with the studs and push the wheel towards the car. Once the wheel is hung on the studs, thread a lug nut on. Cars with lug bolts come with a thread blank, a bolt with no head. Thread this onto the hub to act as a stud to "hang" the wheel on.

Tightening Lug Nuts-Once you get that first lug nut you should tighten the lug nut all the way. The important thing here is to make sure the wheel sits flush against the hub. Push the wheel back as you tighten. You do not want the wheel to be cocked on the studs. Once that first lug nut is in place the plenty of stud thread should be exposed to easily engage the rest of the lug nut. Snug all the nuts in place. Lower the car off the jack. The final step is to torque the lug nuts. Torque should be done with the car on the ground. Most lug nuts are speced to be tightened between 80-100 foot pounds. A foot long wrench handle and 100 pounds will generate 100ft/lbs. So if your lug wrench is 16 inches and you weight 150lbs. A little more than half your weight on the end of the wrench will suffice. You should also tighten the lug nuts in a cris cross pattern to ensure the wheel is seated properly. Then go back and re-torque the first and 2nd lug nut.

And just like that, you are rolling down the highway again on your way to stuff your face full of Turkey and mash potatoes.

Update: I got into a debate last night on whether it is proper to tighten the first lug nut all the way, or if all the lug nuts should be threaded on prior to them being tightened. First off tightened is different then torqued. The idea that all the LNs should be installed then tightened in a criss cross pattern is to insure that the wheel sits on the hub flush, however it does not guarantee this. You can easily tighten the first LN and have the wheel cocked sideways on the studs and then only when the second LN is tighten pull the wheel flush. Doing it this way might bend the wheel or jam the wheel against the studs and still be crocked. Tightening the first LN and taking extra care to make sure the wheel sits flush has a few benefits. You can make sure the wheel is flush because you can see the length of stud exposed in the wheel holes without the rest of the LN in place, and insure that they are equal length. Once the wheel is set you don't have to worry about it and just drive the rest of the LNs home. Some wheels have very deep LN holes and it is difficult to start the LN on the threads of the studs. The greatest benefit I find is that with the wheel seated all the way, is that you have the maximum amount of thread exposed to work with.

4 comments:

  1. What about part 3? Changing a tire on the trail.

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  3. Changing a car tire is the most irritating thing. You know how to change it as the process it easy but it takes longer time and patience. Going to the repair center just for tire change is just waste and it's better to do it by own. Thanks for the step-by-step instruction; it would be helpful for the new users. Besides tire change, a user must know the common Car Care Tips for simple maintenance.

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  4. Yeah, it is just the easiest stuff under repairing that you can do to your car. Often, people take a longer time to do it but I found it fun. I don't have knowledge in repairing any other issue related to my car. For all that, I depend on my service center German Auto service Safety Harbor, FL. Thanks for writing so much about tire changing. I thing few fellows will learn a lot from it. Keep posting.

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