Is it safe to drive an unbalanced car?
WHEEL BALANCE AND MPG
GOAL: To understand how properly balanced tires can improve vehicle mpg.
OBJECTIVE: The student will:
1. Learn how to identify an improperly balanced tire.
2. Understand the relationship between tire imbalance and reduced mpg.
LESSON/INFORMATION: Rarely do technicians associate poor tire-wheel balance with reduced mpg. Most technicians associate properly balanced tires with increased tire life and a smooth, controllable ride. However, when tires are not properly balanced, tire to road traction is reduced. Reduced traction results in tire slippage, a source of energy loss.
Figure 1. Condition of balanced and unbalanced tires and road contact.
Loss of fuel economy may range from minimal to considerable, depending on the degree of tire imbalance and the vehicle’s operational speed. The greater the imbalance and the greater the speed, the greater the loss of traction and a corresponding loss of fuel economy. The loss of fuel economy due to out-of-balance wheels applies only to the driving wheels. Improperly balanced non-driving wheels affects only ride and tire life. Unbalanced tires exhibit a spotty, erratic, cupped wear pattern. Force dynamics create this wear pattern. Energy is lost scuffing away the rubber. A tire 1 ounce out of balance and traveling at 60 mph exerts 7.73 pounds of excessive force each revolution! Energy is lost! See Figure 2 for tire wear pattern.
Figure 2 Illustration courtesy of Moog Automotive.
Tire life impacts energy reserves since crude oil is a raw material used to produce tires. Tires that wear out prematurely waste oil stock since replacements are required. Disposal of used tires is an environmental problem. Presently, efforts are underway to use spent tires as a fuel source and as an extender for road construction base material.
ACTIVITY: 1. Inspect several vehicles. Notice tires that show signs of imbalance, especially driving wheels. See Figure 2 for a typical imbalanced tire wear.
a. Does the vehicle vibrate? ____Yes ____No
If yes, speed at which vibration is most prominent: ____________ mph.
3. With owner/driver’s permission, road test the vehicle and verify tire imbalance and speed(s) where imbalance is most perceptive. NOTE: BE SURE TO WEAR SEAT BELT. OBSERVE TRAFFIC LAWS AND SPEED LIMITS.
4. Perform a normal tire/wheel inspection and wheel balance.
5. Road test again for accurate repair.
6. Request owner/driver report on this vehicle’s mpg for the next three tanks of fuel.
INFORMATION CHECK Directions. Indicate whether the statements below are true or false. If false, please correct the statement to make it true.
1. _______ Only imbalanced driving tires cause loss of mpg.
2. _______ Tires that wear out prematurely deplete crude oil stock.
3. _______ Any imbalanced tire results in loss of mpg.
TEACHER’S NOTES Rarely do student technicians correlate improper wheel balance with mpg. Loss of traction on driving wheels causes loss of mpg. This exercise will help students understand this principle.
ANSWERS TO INFORMATION CHECK: 1. True
3. False — Non-driving tires will still wear prematurely and cause a poor ride and possibly reduce steering control (the front tires of a rear wheel drive vehicle) but they will not affect mpg.
RECOMMENDED READING: Steering Suspension and Brakes. Pages 50-51
Principles of Wheel Alignment and Service, 3rd Edition. Pages 140-142
REFERENCES: Ellinger, Herbert E. and Richard Hallaway. Automotive Suspension, Steering, and Brakes. Prentice Hall, Englewood Cliffs, NJ. 1980.
Bacon, E. Miles. Principles of Wheel Alignment Service, 3rd Edition. McGraw Hill, NY. 1985.
Birch, Thomas W. Automotive Suspension and Steering System. Harcourt Brace Jovanovich, Orlando, FL. 1987.
Coghlan, David A. Vehicle Chassis Systems. Duxburry Press, North Scituate, MA. 1978.
Comments or questions to: TechAsmt@LA.GOV
How Long Can You Drive On Unbalanced Tires? Is It Safe?
Over time, your tires will naturally become unbalanced. This is because as your tires rotate, they will start to develop an uneven wear pattern. While this is not a problem at first, it can eventually lead to your tires becoming unbalanced.
When your tires are unbalanced, it means that they are not evenly distributing the weight of your car. This can cause your car to vibrate and make noise, and it can also lead to premature tire wear. So, how long can you drive on unbalanced tires? It is safe?
2-3 months is about the maximum you should go before getting your tires rebalanced. After that, the uneven wear will start to cause problems with your car’s handling and can lead to a blowout. So it is important to get your tires rebalanced as soon as you start to notice an issue. If you wait too long, it could end up costing you a lot of money in repairs.
Consequences of Driving on Unbalanced Tires
1. Extensive Tire Wear and Tear
Driving on unbalanced tires can lead to uneven tire wear, which will shorten the life of your tires. This can be a particular problem if you have expensive tires. If you notice that your vehicle is pulling to one side or vibrating excessively, it’s time to have your tires balanced.
2. Increased Fuel Consumption
This is because the unbalanced tires create drag, which makes your engine work harder. This not only wastes fuel but also puts unnecessary strain on your engine, which can lead to increased wear and tear.
3. Safety Hazard
The most important consequence of driving on unbalanced tires is that it’s a safety hazard. Unbalanced tires can cause your vehicle to lose traction, making it more difficult to control. This can lead to accidents, and in extreme cases, even fatalities.
4. Consistent Vibration
The final consequence of driving on unbalanced tires is that it can cause a consistent vibration. This can be extremely annoying, and it can also lead to other problems such as headaches
If you’re experiencing vibration while driving, it’s important to have your tires balanced as soon as possible.
5. Impact on the Suspension System
Driving on unbalanced tires can cause damage to your suspension and steering components. This is because the unbalanced tires put additional strain on these components. Over time, this can lead to premature wear and tear.
How Mechanics Balance Wheels
The first step a mechanic will take is to inspect the tires and wheels. They will look for any obvious signs of damage, like cracks or missing chunks of the tread. They will also check to see if the wheel is bent.
When there are no signs of damage, the mechanic will move on to the next step: measuring the weight of the wheel.
Measuring the Weight of the Wheel
The weight of the wheel is important because it needs to be balanced. If it is not balanced, the tire will not rotate evenly. To measure the weight of the wheel, the mechanic will use a device called a balance machine.
This machine has sensors that measure the weight of the wheel and calculate how much it needs to be balanced.
The mechanic will add weights to the outside of the wheel until it is balanced. This involves adding small metal weights to the wheel until the sensors on the balance machine show that the weight is evenly distributed.
Tire rotation is when you move the tires from one position to another. This helps evenly wear down the tread on the tires. The most common pattern is to move the front tires to the back and the back tires to the front. But other patterns can be used as well.
Benefits of Wheel Balancing
It is important to have your wheels balanced for several reasons including:
1. Smoother Ride
Balanced wheels will help your vehicle ride smoothly. This is because the weight of the wheel and tire are evenly distributed, so there are no areas that are heavier than others. This can lead to a more comfortable ride for you and your passengers.
2. Better Fuel Economy
This is because when the weight of the wheel and tire is balanced, there is less rolling resistance. This means that your engine doesn’t have to work as hard to move the vehicle forward, which can lead to better fuel economy.
3. Longer Tire Life
Unbalanced wheels can cause tires to wear unevenly, which can lead to premature tread wear. This can ultimately shorten the life of your tires.
4. Protect Vehicles Suspension
The suspension system of your vehicle is designed to cushion the ride and absorb shocks from bumps in the road. When the weight of the wheel and tire is unbalanced, it can put extra strain on the suspension components, which can lead to costly repairs down the road.
One of the most important reasons to keep your wheels balanced is for safety. Unbalanced wheels can lead to vibration, and if left unchecked, this can cause the wheel to come loose from the vehicle while driving.
This is a serious safety hazard that can be avoided by simply having your wheels balanced regularly.
Signs of Unbalanced Wheels
You may feel vibrations in the steering wheel, through the seat, or even in your seat belt. The severity of these vibrations will depend on how unbalanced your wheels are.
The steering may feel heavier than usual or may pull to one side. This can be dangerous, especially at high speeds.
Uneven Tire Wear
When your tires are unbalanced, you’ll likely see uneven wear on the tread. This can cause your tires to wear out more quickly and may even lead to a blowout.
Worn Out Suspension And Steering Components
This can cause these parts to wear out more quickly, which can lead to expensive repairs. It can also make your car less safe to drive.
Frequently Asked Questions
How Long Can You Drive on Unbalanced Tires?
2-3 months is the maximum time you should drive on unbalanced tires. When your tires are unbalanced, it is best to have them balanced as soon as possible. Driving on unbalanced tires can cause premature tire wear and may impact your vehicle’s handling.
What If I Ignore Unbalanced Tires?
When you ignore unbalanced tires, you risk tire failure. Tire failure can cause a blowout, which can lead to a serious accident. Additionally, unbalanced tires can damage your vehicle’s suspension.
How Much Does It Cost to Balance Tires?
The cost of balancing tires varies depending on the type of vehicle you have and the size of your tires. Most tire balancing services range from $15 to $75.
Do You Balance All Four Tires at Once?
No, you do not need to balance all four tires at once. However, it is recommended that you balance your tires in pairs. This will help ensure that your tires wear evenly.
What Causes Tires to Become Unbalanced?
The most common reason is due to normal tire wear. As your tires wear, they become lighter and more susceptible to becoming unbalanced. Additionally, driving on uneven surfaces can cause your tires to become unbalanced.
How Do I Know if My Tires Are Unbalanced?
When your vehicle is vibrating or shaking, your tires are likely unbalanced. You can also check your tires for uneven wear. If you see that one side of your tire is wearing more than the other, it is probably because your tire is unbalanced.
If your tires are starting to feel unbalanced, you can continue driving for another 2-3 months on them before having to do the rebalancing. Not doing it will further increase the wear on the tires, leading to stability and safety issues.
Driving on unbalanced tires is not safe, so investing in a rebalancing procedure is going to be worth it no matter what kind of a vehicle you drive.
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