Wheel alignment and tire balance
These sound similar but they’re not. Confused? Don’t get all wobbly, read on.
Basically, balance has to do with how the tire rotates on the axle, while alignment refers to setting the angles of the wheels so the vehicle runs straight without pulling to one side.
First, here’s a great deal on a front end alignment:

Let’s look at tire balance and wheel alignment in more detail:
Tire balance
When the wheel rotates, asymmetries of mass may cause it to hop or wobble. So if one of your tires is out of balance, instead of spinning gracefully like a ballerina it is more likely to flop around like a kid’s top with a piece of gum stuck to one side.
Our go-to-guys at Gatto’s can put your tires on either a Hunter or Coats computerized wheel balancer and use correction weights in the proper spots to counteract the unbalance.
Want to know more? http://en.wikipedia.org/wiki/Tire_balance
Proper alignment
Proper alignment is when all suspension and steering components are sound and the tire and wheel assemblies are running straight and true. Most of our Gatto’s stores are equipped with state-of –the –art Hunter Laser Alignment machines to keep you easing on down the road. The machine was going to be called the ease-on-down-the-road-o-matic, but for some reason that idea didn’t catch on.
Proper alignment is necessary for even tread wear and precise steering. Uneven tire wear, or changes in your vehicle’s handling or steering response (i.e. pulling to one side), can indicate misalignment.
Your vehicle may need a “front-end” alignment and some vehicles may need a “four-wheel” alignment, depending on your type of vehicle and the symptoms you are experiencing.
The moderate cost of having your vehicle aligned can more than pay for itself in tire mileage, performance and comfort.
An out of alignment or out of balance tire can increase rolling resistance, which means the engine has to work a little harder to push the vehicle down the road. This decreases your fuel mileage, not to mention decreases your tire treadlife as well.
So wobbles and pulls to the side are your vehicles way of telling you, “hey, I’m costing you money that you don’t need to be paying. Get me in to Gatto’s and put me back on the straight and true.”

http://en.wikipedia.org/wiki/Wheel_alignment
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