Maintaining the tire balance on your vehicle is critical to receiving satisfactory service from your tire investment. In addition to providing a smooth ride, balancing is a key component in tire wear. The focus of this article is to help you understand the balancing process and to know why it is important to keep your tires balanced throughout their tread life.
For those of you who think that tire balancing isn’t that important, consider some industry trends that may help you rethink the issue. Perhaps the most compelling argument for precision balancing comes from an obvious fact: vehicles are being made lighter and lighter. The heavier cars of yesterday actually helped smooth out the ride by dampening many vibrations before the driver could feel them. The softer suspensions also had the same effect. Another factor is tire technology. Generally, more responsive tires with lower profiles (which send more road feedback to the driver) are being used in today’s style- and performance-oriented market. As a result, the slightest imbalance (as little as half an ounce) can be felt in most modern vehicles. This is significantly less than the average of ten years ago. For those of you who have plus-sized your tires and wheels, balancing is even more critical. When a tire is mounted onto the wheel, two slightly imperfect units are joined to form an assembly weighing forty pounds (this is the average for cars). The chance of this assembly having absolutely precise weight distribution about its radial and lateral centers is virtually impossible. Remember that all it takes is half an ounce of uneven weight distribution for a vibration to be felt.
A “lever-less tire machine” (LTM) is the best way to have your tires dismounted or mounted on your wheels. LTM uses a different technology to break the bead and dismount the tire from your fancy wheels without scratching the surface of the rim or tearing the tire. I will try to explain why this is by comparing the new technology of a LTM to that of a traditional tire machine.
A traditional tire machine uses a metal plate connected to hydraulics that squeezes inwards to break the seal of the tire from the rim. The plate will fit just inside the small space created between a tire and wheel. Normally, to break the seal a number of passes must be done around the circumference of the wheel on both the front and rear to loosen up the tire sealed against the bead of the rim. When this is being done imagine the amount of pressure being applied to the tire and the rim itself (hundreds of pounds of pressure). When the tire bead is being broken on the inner seal (the back of the rim) all of this pressure is pushing on the face or the pretty side of your wheel (the plate is used to break the bread one side at a time and as it squeezes inwards on the back then the front of the wheel is leveraged against a solid flat surface) and one small slip can scratch the face of the wheel. Also, the metal plate that breaks the bead can slip out of the tiny space between the tire and rim and usually scratches the wheel when this happens.
Once the bead is broken on a tire then it can be dismounted. Traditional tire machines use a metal guide head and a lever to pull the lip of the tire up over this guide and spin the tire off. If the tire is a run flat, low profile, or just tightly sealed on the rim then it is very easy for that metal guide head to bend down onto the face of the wheel and scratch it while the tire is spun off. Also, some wheels have protruding spokes that can be near impossible to avoid damaging when the tire is being dismounted.
Almost of greater concern is that when dismounting a stiff run-flat or low profile tire using a traditional tire-changing machine, the tire can actually tear on the metal guide head as it is being taken off. These tears are not always completely damaging to a tire so many times the tire is remounted and there is no way to know that the tire was damaged because when mounted back on your rim it will look completely normal.
The “lever-less tire machine” uses a different method of breaking the bead and dismounting the tire so that scratching the wheel or damaging the tire does not happen. To break the bead there are two hardened plastic rollers on either side of the rim that are set exactly to the point just between the wheel and tire and then locked into place. Taking turns, the wheel is spun and each roller is slowly lowered to apply pressure on the tire all the way around the wheel. The tire is slower broken away from the bead of the rim without applying massive amounts of pressure to the rim itself. Once the bread is broken there is another hardened plastic arm that slips into the tire, catches the edge of the tire, and literally lifts the tire up and over the wheel avoiding spokes and applying zero down pressure on the face of the wheel. Without the use of a lever there is no pressure placed on a guide head and no risk of damaging or tearing the tire.
Those of us who know what a Road Force Balancer is, know that there really is no comparison with a standard balancer. For those of you who do not know what a Hunter Road Force balancer is please read on and I will do my best to explain.
A standard balancer is great for balancing steel wheels on larger trucks or the older style of wheels that use clip on weights for both the outer and inner lips. However, the style of wheels is changing and most wheels require the use of stick on weights that are applied to the inner barrel. A standard balancer is not ideal for measuring the exact amount if weight to be applied to the inner barrel of wheel. For starters, every wheel is different because the offsets are different even among different models of the same manufacturer. A BMW 3 series will have wheels with a much different offset than a 5 or 6 series BMW. The difference is that the weights must be applied just behind the spokes and on a standard balancer there is no way to tell the machine exactly where this is.
Standard balancers know the diameter of a wheel, how wide the wheel is, and how far away it sits from the sensor that measures the run out. In a standard balancer all it is doing is looking for the slight variations of out-of-round in the wheels and tire assembly. The weights help to even out a side-to-side wobble (lateral run out) or an up and down wobble (radial run out). What is missing from the measurements is the amount of force the tire can throw off.
When balancing using a Hunter Road Force machine we are able to tell the machine exactly how far the wheel sits from the sensors that are taking the measurements, exactly the distance to just behind the spokes (where we must apply our stick on weights), the width of the wheel, and the diameter. Most importantly, a roller will apply about 1000lbs of pressure to the wheel while it is spinning to replicate what the wheel will act like when the on the road with the weight of a car on it. This roller can measures the amount of weight the tire can throw off while it is spinning. This is known as “road force”. Road force is present in new and old tires – sometimes, even more so in new tires which is caused from stiffness, lack of stiffness, or weak spots in the sidewalls of the tires. By reading the run out of the wheel and tire assembly in conjunction with the road force measurement the Hunter Road Force machine will virtually always get a wheel perfectly balanced. While the Hunter Road Force Balancer is taking measurements it looks at both the rim run out and tire run out to see if they are within industry specific tolerances and if the wheel and tire assembly is out of tolerance there are a whole host of other tests to determine if the excessive road force is caused by the rim or the tire. In most cases, rotating the tire to a different position on the wheel, or even using the tire on a different rim can eliminate excessive road force.
What the Hunter Road Force balancer can measure is not possible on a standard balancer. Because the style of wheels used on more cars today are alloy wheels that require stick on weights it is necessary for more styles of cars to have this kind of balancing done. In our own experience we have already had customers who found that after having us Road Force Balance their wheels it was the smoothest ride they had ever experienced while driving their car. Even when it was new!