Alignment means ensuring the wheels are properly straightened and the car rolls in a straight line. If the wheels are misaligned, the car might veer slightly when moving.

Imagine you have a bike, but it's handle bar is kinda turned to the left. Not too bad, but annoying. That's one part. Now imagine your bike has two front tires. If one of them is pointed a little to the left but the other is straight, you can see the problem.

The wheels of a car really need to be perfectly aligned. If the left wheel is facing exactly straight, then the right wheel should NOT be 0.5 degrees turned in either direction. But various bumps on the road and general stress may cause little errors like this to develop. Other variations exist where the wheels become just a little bit "off" from perfectly aligned.

This causes increased wear and tear, especially on the tires, and reduced mileage.

Getting that checked and corrected can be done as part of regular vehicle maintenance.

Car alignment is the process of adjusting the angles of the wheels so that they are perpendicular to the ground and parallel to each other. This ensures that the tires are making maximum contact with the road, which helps to improve handling, steering, and tire wear.

In summary, getting your car aligned regularly as part of your service is important to ensure that your car handles properly, has good tire wear, and drives efficiently.

It's making sure all four of your wheels are pointing straight ahead when your steering wheel is centered. If you took your hands off the steering wheel while driving, your car should go straight instead of veering one way or another.

Alignment goes along with tire balancing which makes sure your tires are all straight vertically and the tread lays flat on the road so they don't get worn on one side.

I'm going to follow up with probably a very stupid question.

When I get service, can they simply check for bad alignment and just charge for that If the alignment is good? Or do you typically just pay for an alignment and they align it whether it's out of alignment or not?

You might notice your alignment is poor if the car is pulling a bit one way when your steering wheel is at rest, or if the tire wear is uneven. Otherwise it's probably not worth paying for the alignment service in my opinion.

So what you guys are saying is that cars get joycon drift? 💀

> I get service, can they simply check for bad alignment and just charge for that If the alignment

You can often tell by how the tires are wearing and how the car drives. In theory the "correct" alignment for your car should cause your tires to wear evenly, and when you drive down the road on a flat, level, smooth road, and you let go of the wheel, it goes straight, or maybe drifts a hair to the right. It should not drift to the left.

If the side towards the center of the car is wearing faster then the outside, or other way around, it means the tires aren't "flat" on the ground.

The point of having your alignment done is to make sure the tires wear evenly, the car drives straight easily.

A car gets out of alignment by parts getting slightly bent. Even thick steel parts will slowly bend over time. And alignment is measured in 0.1degree increments. So just a hair off will make your car drive less smoothly. They measure it in 2 directions, plus the difference between the right and left side.

I had an old truck that was off 4 or 5 degrees. It still drove, just... you just had to keep your hand on the wheel to prevent it from turning right. It wanted to turn right, and went through tires quickly.

Driving over bumps, and general wear and tear, can cause the wheel and tires to not line up straight anymore. Even if they are off a little bit, it can cause the tires to wear faster and make steering a little off. An alignment is when they get all of the tires and wheels sitting flat and pointing in the right direction again.

Pretty much. Real bad cases you'll see that 1 tire will be tilted inwards at the top or bottom on a vehicle. When i was a tire tech there was an infogram on one if the workstations that describes it very well, i have a picture of it here somewhere.

Edit found the photo! Useful automotive guide https://imgur.com/a/eyihz3z

The difficulty with this is that most roads are curved or have a slight incline crosswise, to help shed rainwater. This also causes cars to never drive straight even when the wheels are properly aligned. A better indicator of misalignment is tire tread wear patterns.

Also not completely sitting flat because as you turn, you want to maintain certain tire contact, and therefore need to compensate for that. There's also plenty of things with suspension abs even driving style that impact this, which is why it's important to get them aligned more than just the once. Each alignment is an approximation of what it will need to be, but those factors will almost certainly change over time

If your car is driving straight and the tires are wearing evenly the alignment is good or good enough. To check the alignment takes almost as much work to do the alignment because most of the work is putting on the equipment. Some cars even make the technician put a weight in the front seat to simulate the driver, so you're going to pay a shop nearly the same amount of money to just do an alignment. If there are no symptoms of a bad alignment, there really isn't a need to check it. The symptoms to look out for are the car pulling to one side or the other on the highway without input from the driver. e.g. you let go of the steering wheel and it starts drifting to the left consistently, if it pulls in a different direction every time, it could be the crown in the road. Uneven tire wear on one of the edges. e.g. your front driver's side tire's inside is worn, but the outside isn't. If the same tire has both the inside and outside worn but the middle is OK, it's a sign that you need to inflate your tires, if just the middle is worn, then you're overinflated, but if only one edge is worn, it's likely an alignment issue

Poor alignment can also cause uneven and quicker wear on your tires reducing their lifespan. It also reduces your mileage per gallon a bit as well.

A car's wheels have to be alligned properly, with each other and the steering wheel. Driving around, hitting potholes, debris, curbs and other things cause a lot of wear and tear and can cause the wheels to go out of allignment, which causes worse handling and accelerated tire wear. So cars have to have their wheels checked and alligned regularly.

Dang, thank you!

Is it true that setting up a car to have the alignment checked is most of the work of adjusting it too? Like you pretty much pay for an alignment regardless if it needs it.

[removed]

Yes. You have to put it on a lift, level the steering wheel, attach sensors to each wheel, calibrate it, and pull up the specs for the vehicle. The actual alignment part involves then adjusting a bolt or two, unless it’s really badly out of spec.

The worse problem is when one wheel is pointing left and the other right. If the only problem was the car not rolling straight the driver could turn the steering wheel, and then it‘s straight. When the wheels are facing in opposite directions the driver can’t correct for this and actually may not be aware of it as it may not cause the car to turn, but with the tires (slightly) sliding to the side instead of rolling straight ahead, they will wear out much faster then they should.

I once had a friend ride in my passenger seat for less than five minutes before telling me I needed a wheel alignment. Turns out he was right. How can you tell from the feel of a car that it needs an alignment?

If you have to turn down a straight road, it's most likely your alignment. If the car is badly out, it will understeer in one or both directions.

You can usually tell by the way the car pulls when nobody is touching the wheel or how you correct. If the car always pulls to the left, you'll always correct to the right. Also if the steering wheel is crooked when the wheels are straight you need an alignment.

Ideally your car will always be Lawful Good; it will drive better and cause less wear and tear on itself over time. But shoddy roads, rage-inducing drivers and lengthy traffic stops can tend to cause the car to slide slowly but inexorably through neutral to chaos and evil. Regular maintenance and the occasional exorcism can keep this tendency in check, however.

Ok, maybe the steering wheel was slightly turned to go straight. I always assumed he felt a wobble or something

If off by a little bit like 2° and going on a windy highway it's a bad time..

Yes - there used to be a “check the alignment” service but that’s pretty much a thing of the past.

If you know the feeling, sometimes you can feel the resonance through the vehicle. He could have also noticed you were constantly counter steering as well

Wobble is wheel balance

He probably noticed that you never let go of your wheel, or the times that you did the car veered off

It's probably the best way to spot if someone's not servicing their car regularly, considering wheel alignments are ultra cheap and are sometimes even done for free alongside a service.

Do people often let go of the steering wheel while driving? 😲

If I'm going slow through a suburban area I'll often let go for a second here or there, or just hold on with a couple fingers with my hand on my lap. It's not a good habit, but if your car drives straight you'll feel far more confident

I had a car that was so badly out of alignment that it shook just driving a straight line. Not saying this guys was that bad, but at a certain point it’s definitely noticeable even if you’re not looking for it.

[removed]

Wobble can be a million things; wheel balance is one of those things, but only one. Could be alignment, bad steering dampener, bad power steering system, bulged tire, loose steering components, loose suspension components, or brake disc warping, and that's not even a full list.

Just creeping to the side is obviously corrected by the steering wheel. The obvious issue are the wheels each steering to different sides.

At least in the UK, some garages will do the free alignment check if your car is in for other work. If it's out of alignment, it's an easy upsell for them.

There's actually a bit more to it than just "all the wheels pointing straight ahead". The front wheels in particular usually have three settings - camber, caster, and toe. Camber is the vertical angle the wheel meets the road at ( left - right tilt ), caster is the steering angle ( forward / aft tilt ), and toe is the horizontal alignment of the wheel ( toe-in or toe-out ). If any or all of those adjustments are incorrect ( due to normal wear and tear, or hitting something on the road ), your tyres will wear in an uneven and premature way. These settings need to be periodically adjusted as suspension and steering parts wear and settle over time.

I had a crooked steering wheel for a while - there was a recall to replace some cable inside the wheel, and they put it back on slightly crooked. So it drove completely straight without needing any steering input, with a 5 degeee angle on the wheel. It was mostly unnoticeable on shorter drives requiring more manuvering, but very annoying on long highway drives.

It required an alignment to fix it.

Please read this entire message

Your submission has been removed for the following reason(s):

Straightforward or factual queries are not allowed on ELI5. ELI5 is meant for simplifying complex concepts.

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.