- Feb 2, 2006
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Match Mounting to Enhance Tire & Wheel Uniformity
Tire and wheel manufacturers continually develop new manufacturing methods to enhance the uniformity of their products because radial runout, lateral runout, force variation and imbalance can affect a vehicle's ride quality.
Match mounting tires on wheels is a process where a tire's installed position on the wheel is specifically selected to help minimize the final combination's force variation and/or imbalance. One match mounting procedure aligns the tire's measured high point of radial force variation with the measured low point of the wheel's radial runout. The other simply aligns the tire's lightest spot with the wheel's heaviest spot.
Original Equipment (OE) tire suppliers are required to mark the tire's "high point" while OE wheel manufacturers mark the wheel's "low point." This helps the vehicle manufacturer match mount combinations that maximize new car ride quality while reducing the amount of balancing weight.
Today, many vehicle manufacturers require the use of a temporary tag applied to tires and wheels that are removed before the vehicle is put into service. Unfortunately this means that there are no permanent marks to reference later.
There was a time when the valve stem hole on standard wheels indicated the optimum place to which the tire should be match mounted. However, with the advent of styled, steel wheels and aluminum alloy wheels, the stem position evolved into an aesthetic issue rather than being a uniformity indicator. Add to this the probability of wheels retaining their original runout after thousands of miles of use and you can understand that simply mounting the tire so the colored dot is at the valve stem is no longer required practice.
We have found that the only way to accurately match mount replacement tires on used original or new aftermarket wheels is to use Hunter tire balancers which have the ability to measure wheel runout and tire force variations under load before the tire and wheel are installed on the vehicle. Using these machines, a colored dot might be positioned anywhere on the wheel relative to each wheel's runout measurement. In the end, the markers have little, if any, relevance when replacement tires are installed.
Mounting and Balancing
For the proper mounting of tires and wheels not purchased as a pre-mounted Tire & Wheel Package, be sure to observe some basic precautions:
* Mounting and balancing should be done by a professional, using equipment designed for the job
* Both tire beads are securely mounted
* The wheel is not bent or damaged
* There is no buildup of dirt between the hub and the wheel
* All of the lugs have been properly torqued
* The wheel is securely seated on the hub
The definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. In English, that would translate to...A balanced tire is when the mass of the tire, when mounted on its wheel and the car's axle, is uniformly distributed around the axle. Even easier yet, how about...there are no heavy spots.
Balanced tires can be the difference between a good or bad driving experience. Some cars (and drivers) are more sensitive to an out of balance tire than others, but no one is happy with a vibration.
An out of balance tire can adversely affect ride quality, shorten the life of your tires, bearings, shocks and other suspension components. If you have a vibration that is dependent on speed, and usually becomes noticeable around 40-45 mph and increases as your speed increases, it's probably balance related. The other primary cause of vibrations is that the tire and wheel assembly isn't perfectly round. Face it, if we go out far enough past the decimal point, nothing is perfectly round. This includes your wheels and tires. The problem is when the high spot on the tire, and the high spot on the wheel end up being matched to each other. This effectively doubles the amount of "hop" or runout. If re-balancing doesn't cure the vibration problem, have your professional installer check the runout of the tire. If there is a "hop", many times the problem can be fixed by simply rotating the tire on the wheel slightly. The technician should loosen the tire on the wheel, and turn it 180 degrees, and reinflate the tire after relubricating the bead. The runout should be significantly reduced or eliminated, and if it's not, try it again, but this time rotate only 90 degrees, and if that doesn't work, try 180 degrees on the third try. Done this way, the high spot on the tire has been tried at each quarter of the wheel. At one of those points, the tire should be good and round. At that point, rebalance the tire, and go for a test drive. If the vibration persists, the problem is either in the tire, or elsewhere in the vehicle.
Tire & Wheel Package Installation Instructions
It usually takes only minutes to install tires and wheels on your vehicle; but remember, they'll probably be on for 3,000 miles or more, and will roll over a million times before it's time to rotate them. To make those miles as pleasant as possible, you need to install your new Tire and Wheel Package correctly.
Check Tire Positions
If you selected directional tires and/or asymmetric tires, the first step before installing them is to match each tire and wheel to its final position on your vehicle. To prevent mistakes, actually set each wheel and tire around your vehicle just as race teams do for pit stops.
Install New Pairs or Tires on the Rear Axle
When tires are replaced in pairs, the new tires should always be installed on the rear axle and the worn tires moved to the front. The reason is because new tires on the rear axle help the driver more easily maintain control on wet roads because new, deeper treaded tires are more capable of resisting hydroplaning.
Tire & Wheel Package Ride Uniformity Confirmation
Smooth-rolling tires and wheels can be the difference between having a vibration-free driving experience or a shaky one. If the tire and wheel tolerances are not examined, corrected, or are allowed to "stack up" rather than "cancel out" each other, the possibility of a balance or road force induced ride vibration exists. Because of this, Tire & Wheel Packages don't ship from The Tire Rack unless they're Hunter-Balanced and Road Force® approved!
Tires are made up of internal beads, body plies and belts that are encased in rubber, assembled and cured. Alloy wheels are cast, cooled and machined. And even though they both are built to tight tolerances, there is bound to be some unavoidable weight imbalances during the manufacturing process.
When you consider that a typical passenger car tire mounted on an alloy wheel weighs about 40 pounds, it's amazing that the total amount of imbalance is typically no more than three to four ounces, or about one-half of one percent. So, if the tire and wheel combination isn't balanced with add-on weights, being off even an ounce or two can cause vibration at highway speeds. Heavier tire and wheel combinations, especially those used on light trucks, require more weights to maintain the same low percentage of imbalance.
info extracted from :
http://www.tirerack.com
Tire and wheel manufacturers continually develop new manufacturing methods to enhance the uniformity of their products because radial runout, lateral runout, force variation and imbalance can affect a vehicle's ride quality.
Match mounting tires on wheels is a process where a tire's installed position on the wheel is specifically selected to help minimize the final combination's force variation and/or imbalance. One match mounting procedure aligns the tire's measured high point of radial force variation with the measured low point of the wheel's radial runout. The other simply aligns the tire's lightest spot with the wheel's heaviest spot.
Original Equipment (OE) tire suppliers are required to mark the tire's "high point" while OE wheel manufacturers mark the wheel's "low point." This helps the vehicle manufacturer match mount combinations that maximize new car ride quality while reducing the amount of balancing weight.
Today, many vehicle manufacturers require the use of a temporary tag applied to tires and wheels that are removed before the vehicle is put into service. Unfortunately this means that there are no permanent marks to reference later.
There was a time when the valve stem hole on standard wheels indicated the optimum place to which the tire should be match mounted. However, with the advent of styled, steel wheels and aluminum alloy wheels, the stem position evolved into an aesthetic issue rather than being a uniformity indicator. Add to this the probability of wheels retaining their original runout after thousands of miles of use and you can understand that simply mounting the tire so the colored dot is at the valve stem is no longer required practice.
We have found that the only way to accurately match mount replacement tires on used original or new aftermarket wheels is to use Hunter tire balancers which have the ability to measure wheel runout and tire force variations under load before the tire and wheel are installed on the vehicle. Using these machines, a colored dot might be positioned anywhere on the wheel relative to each wheel's runout measurement. In the end, the markers have little, if any, relevance when replacement tires are installed.
Mounting and Balancing
For the proper mounting of tires and wheels not purchased as a pre-mounted Tire & Wheel Package, be sure to observe some basic precautions:
* Mounting and balancing should be done by a professional, using equipment designed for the job
* Both tire beads are securely mounted
* The wheel is not bent or damaged
* There is no buildup of dirt between the hub and the wheel
* All of the lugs have been properly torqued
* The wheel is securely seated on the hub
The definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. In English, that would translate to...A balanced tire is when the mass of the tire, when mounted on its wheel and the car's axle, is uniformly distributed around the axle. Even easier yet, how about...there are no heavy spots.
Balanced tires can be the difference between a good or bad driving experience. Some cars (and drivers) are more sensitive to an out of balance tire than others, but no one is happy with a vibration.
An out of balance tire can adversely affect ride quality, shorten the life of your tires, bearings, shocks and other suspension components. If you have a vibration that is dependent on speed, and usually becomes noticeable around 40-45 mph and increases as your speed increases, it's probably balance related. The other primary cause of vibrations is that the tire and wheel assembly isn't perfectly round. Face it, if we go out far enough past the decimal point, nothing is perfectly round. This includes your wheels and tires. The problem is when the high spot on the tire, and the high spot on the wheel end up being matched to each other. This effectively doubles the amount of "hop" or runout. If re-balancing doesn't cure the vibration problem, have your professional installer check the runout of the tire. If there is a "hop", many times the problem can be fixed by simply rotating the tire on the wheel slightly. The technician should loosen the tire on the wheel, and turn it 180 degrees, and reinflate the tire after relubricating the bead. The runout should be significantly reduced or eliminated, and if it's not, try it again, but this time rotate only 90 degrees, and if that doesn't work, try 180 degrees on the third try. Done this way, the high spot on the tire has been tried at each quarter of the wheel. At one of those points, the tire should be good and round. At that point, rebalance the tire, and go for a test drive. If the vibration persists, the problem is either in the tire, or elsewhere in the vehicle.
Tire & Wheel Package Installation Instructions
It usually takes only minutes to install tires and wheels on your vehicle; but remember, they'll probably be on for 3,000 miles or more, and will roll over a million times before it's time to rotate them. To make those miles as pleasant as possible, you need to install your new Tire and Wheel Package correctly.
Check Tire Positions
If you selected directional tires and/or asymmetric tires, the first step before installing them is to match each tire and wheel to its final position on your vehicle. To prevent mistakes, actually set each wheel and tire around your vehicle just as race teams do for pit stops.
Install New Pairs or Tires on the Rear Axle
When tires are replaced in pairs, the new tires should always be installed on the rear axle and the worn tires moved to the front. The reason is because new tires on the rear axle help the driver more easily maintain control on wet roads because new, deeper treaded tires are more capable of resisting hydroplaning.
Tire & Wheel Package Ride Uniformity Confirmation
Smooth-rolling tires and wheels can be the difference between having a vibration-free driving experience or a shaky one. If the tire and wheel tolerances are not examined, corrected, or are allowed to "stack up" rather than "cancel out" each other, the possibility of a balance or road force induced ride vibration exists. Because of this, Tire & Wheel Packages don't ship from The Tire Rack unless they're Hunter-Balanced and Road Force® approved!
Tires are made up of internal beads, body plies and belts that are encased in rubber, assembled and cured. Alloy wheels are cast, cooled and machined. And even though they both are built to tight tolerances, there is bound to be some unavoidable weight imbalances during the manufacturing process.
When you consider that a typical passenger car tire mounted on an alloy wheel weighs about 40 pounds, it's amazing that the total amount of imbalance is typically no more than three to four ounces, or about one-half of one percent. So, if the tire and wheel combination isn't balanced with add-on weights, being off even an ounce or two can cause vibration at highway speeds. Heavier tire and wheel combinations, especially those used on light trucks, require more weights to maintain the same low percentage of imbalance.
info extracted from :
http://www.tirerack.com