Valve stem location on Performance tires
Jun 15, 2008, 12:00 PM
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Valve stem location on Performance tires
I recently purchased a set of Z1 star spec's had them mmounted and then noticed that the valve stems did not align with either the yellow or red dots. I knew racing tires in particular marked the sidewall for valve stem location. I did not know why there were 2 dots on tire one yellow and red. Since I was going back to tire shop and have them fix mount. I figured I would do some research. Here is one article i found. If you already balanced with weights it might not matter but it also might change the number of weights needed me thinks. see the article below
TIRE MATCH MOUNTING & CUSTOM WHEEL HANDLING
Mavrigian, Mike (is the author)
Some of the most common types of work done on performance vehicles involve the wheels and tires. This overview of tire and wheel-handling procedures provides information you'll need to keep your customers rolling smooth and straight.
Adding performance vehicle owners to your customer list can give a huge boost to your shop's bottom line. These owners may be demanding-even picky-but they'll pay well to get the job done exactly the way they want it.
Some of the most common types of work done on performance vehicles involve the wheels and/or tires. The wheels are one of the most visible parts of a vehicle, so any work done on them must be top-notch-meaning clean, pretty and accurate.
Custom wheel service can be broken down into two primary topics, essentially-tire match mounting and custom wheel handling. Since you'll never mount a wheel without a tire, we'll cover the ins and outs of tire match mounting first.
What Is Match Mounting?
Match mounting involves positioning the tire onto the wheel to minimize or eliminate thefinal combination of radial force variation and/or imbalance (radial force variation is explained later in this article). One match mounting approach involves aligning the tire's point of maximum radial force variation (its high spot) to the wheel's radial low spot (where the wheel's radial runout is the lowest). This is called the Uniformity Method. The other approach involves simply aligning the tire's lightest balance point to the wheel's heaviest balance point, called the Weight Method.
OE tire suppliers are required to mark a tire's radial runout high point, and OE wheel makers are required to mark a wheel's radial runout low point. This makes it easy for the OEMs to match-mount tires to wheels from a radial force variation standpoint during production. In some cases, these marks are made with paint dots that help service technicians remount tires down the road. However, sometimes these marks are made using temporary stickers, which either fall off or are removed after mounting. This leaves no readily visible reference marks for the tire technician for future service.
If a tire does feature color dots on the sidewall, one or two dots may be used. A red dot indicates the tire's radial runout high point. A yellow dot indicates the tire's point of least weight, from a balance standpoint.
For decades, it was common practice in the aftermarket to mount a tire so its red dot aligned with the wheel's valve stem, since the valve stem area was normally assumed to be the wheel's lowest point of radial runout. Aligning the tires high point to the wheel's low point (theoretically) reduces or eliminates the chance of developing a radial force variation (RFV) in the tire/wheel assembly.' RFV (again, an issue of runout, not imbalance) can cause a vibration that might be mistakenly diagnosed as an imbalance problem.
Times change. With the advent of styled custom wheels, the valve stem location may no longer indicate the wheel's low radial runout spot. In other words, it may no longer be viable to assume that aligning a tire's.red dot to the wheel's valve stem will address any potential RFV issues.
Consequently, a procedure that was once easy has now become complicated. The only way to accurately matchmount a tire to a wheel is to actually measure tire and wheel runout. The end goal remains the same: to align the tire's high point to the wheel's low point. The wheel itself can be easily checked for radial runout by mounting it to a hub and slowly rotating it while monitoring the rim edge with a rigidly mounted dial gauge. However, the only acceptable method to check the assembled tire/wheel package for radial uniformity under load is to use a state-of-the-art wheel balancing machine that features a load-roller that applies road-simulated load to the inflated tire. Such a machine will not only check for dynamic balance but will also locate the tire's high spot. If this high spot doesn't correlate to the wheel's low spot, the machine will let you know where to relocate the tire on the wheel to minirnize RFV
If you don't have access to a roadwheel type of balancing machine, and you don't know where a wheel's lowest radial runout spot is located, you can default to using the Weight Method, which involves aligning the tire's yellow dot to the wheel's valve stem.
As you can see, tire/wheel match mounting isn't a cut-and-dried method. Your approach to match mounting will depend on several variables:
* whether the tire is runout- and weight-matched,
* whether the wheels low runout spot can be determined, and
* whether you have access to a loadapplying balancing machine.
Regardless of the specific approach you take, it's important to understand that "stacked-up" runout and imbalance conditions can be addressed. Of course, once tire matching has been accomplished, the mounted package must then be checked and corrected for dynamic balance.
There are two types of radial runout -static and dynamic. Static runout, as we noted earlier, refers to the high spot of the tire, a physical characteristic that can be measured with no load placed on the tire. Radial force variation, however, refers to a dynamic runout condition, which occurs only when the tire runs at speed, under load, due to variations in construction stiffness.
Radial force variation is so named because the radius of the tire varies according to vehicle speed and load. Of course, any tire, because of its pliability, will vary slightly in radius at the load spot during operation. Although a "radial force" might be the result of a runout area pronounced enough to affect the tires impact on the road, a radial "force variation" may occur if the tire has appreciably different "soft" spots and "stiff spots in the carcass and/or tread or in the sidewall construction. Given the precise quality control processes used by todays tire makers, it's rare that a force variation problem will occur. But when it does, it can be a tricky demon to chase.
Even though no problems may be found as the tire rotates on the balancer, when the tire experiences a load, the transition of the harder and softer sections of the tire may create a series of harmonic vibrations as the various sections of the tire contact and leave the road surface. Depending on conditions, this harmonic may occur once per tire revolution, or in a series of multiple vibrations per revolution. It's possible that this phenomenon may vary according to changes in tire pressure, vehicle speed, individual tire load and road surface conditions, all of which may serve to reduce and/or amplify the vibration problem. In other words, the vibration the driver feels may not occur at any one rate of speed, or on any particular road surface, because the problem may appear only under a specific combination of these variables.
If a tire/wheel will not balance properly, or if a vibration exists after a successful balance job, don't automatically blame the tire. If you haven't checked the hub and wheel for runout, you may be jumping to conclusions. If, however, all balance, static runout and chassis parts variables have been exhausted, then it may be time to suspect a radial force variation problem.
To check for and attempt to actually verify a dynamic radial runout condition, a spin-balancer with a built-in load roller is recommended. This type of balance machine places a load (which attempts to simulate road load) onto the tire as it spins, while monitoring and recording variances of runout. If load variation is found, it may be corrected to an acceptable level via balancing weights. In extreme cases, it may verify that the tire should be replaced.
A minimum range of between .3 and .5 oz. (7 to 14 grams) of imbalance is usually enough for the average motorist to notice an imbalance-induced vibration. If a vehicle is sensitive enough to exhibit noticeable vibration at only .3 to .5 oz. of imbalance, that same amount of vibration may be present with as little as 10 to 15 lbs. of radial force variation, which (although hard to believe) can be caused by as little as .010 to .015 in. of loaded radial runout. Using this as an example, it's easy to see how loaded runout can dramatically affect vibration. In other words, a little bit of "loaded" tire runout variance can produce a notable impact on operating smoothness or harshness.
Handling Custom Wheels
It s extremely important to pay attention to wheel fastener seat styles. Make sure you use the correct style of wheel nut or bolt specified for the custom wheels at hand. Installing the incorrect seat style can damage the wheel bolt hole seats; at worst, it can result in the fasteners loosening on the road, with the wheels disconnecting from the hubs.
The seat refers to the actual contact area between the fastener's head and the wheel. The seat style of the fastener must match the seat style featured on the wheel. If the wrong seat style is used, the wheel simply wul not be fastened to the hub correctly. If the fastener seat style does not match that of the wheel, you'll likely damage the wheel finish and, more importantly, the wheel will eventually loosen and wobble as it moves in relation to the hub.
Seat styles most commonly found include radius, conical and flat ("mag"). These terms refer to the shape of the seat (where the fastener contacts the entry of the fastener hole in the wheel).
Radius seats, also referred to as ball seats, feature a ball shape that mates into a wheel's female radiused ball relief at the wheel's mounting hole.
Conical seats are also called cone seats or tapered seats. This seat style features an angled seat wall. The fastener features a male cone seat, the wheel a female cone entry hole. The most common seat taper angle is 60°.
A mag wheel nut features a flat contact patch at the wheel (and usually a thick flat washer). A mag-style nut may also feature a smooth outer-walled extended shank that helps center the wheel on a lugcentric design, as the shank enters the wheels bolt hole and serves as a guide pin to center the wheel's hole over the wheel stud. Using a capped nut (where the threads do not extend all the way through the nut) may make it difficult to be certain that the stud isn't bottoming out inside the nut. This is why it's important to pay attention to thread engagement length. At a minimum, the nut must engage onto the stud at a depth equal to the stud diameter. For example, if the stud diameter is 12mm, the nut must thread onto the stud by at least 12mm of depth. Also, make sure the stud does not bottom out inside the nut. If it does, it will be impossible to achieve full clamping load.
When it comes to torquing the fasteners, make sure the threads are clean and free of dirt, grease, grit, etc. If burrs or flat spots are found, replace the fastener (both stud and nut). Fasteners are intended to stretch slightly when fully tightened to specification. With regard to automotive wheels, this creates the correct preload required to secure the wheel to the hub.
If the wheel fasteners are undertightened, they'll eventually loosen, resulting in the wheel being damaged or actually coming off the vehicle. If the fasteners are tightened excessively, the wheel stud or bolt can permanently stretch, fatiguing beyond its designed elastic range. Overtightening also can result in fastener failure or, at the very least, in great difficulty during future removal. Especially with todays lightweight alloy wheels and sometimes light (and thin) rotor hats, severe vibrations under braking can occur if wheels are improperly or unevenly tightened.
The only way to ensure correct clamping loads is by tightening all wheel fasteners with a properly calibrated torque wrench. Every custom wheel should be installed by tightening the fasteners with a torque wrench only no exceptions. Using a torque wrench is more time-consuming than using an impact gun, but the owner of a set of custom wheels expects the installation to be performed correctly.
This brings us to the subject of impact wrenches and torque sticks. Torque sticks are basically little torsion bars with a square drive at one end and a hex socket at the opposite end. In theory, a torque stick should begin to twist (and thereby stop rotating the fastener) when a specified torque limit is reached. While the use of such a torque-limiting tool is better than nothing, the best and only proper method is to tighten all wheel fasteners with a hand-held torque wrench. Never use an impact wrench to tighten custom wheel fasteners.
Always install any wheel, regardless of what it's made of, by tightening the fasteners in a crisscross pattern to provide even clamping loads. Uneven tightening can easily result in a distorted hub or wheel, leading to vibration and brake pedal bounce complaints.
Pay attention to torque value accuracy. When you do use a torque wrench, make the final pulls slowly and carefully, creeping up onto the final value, or "click." By abruptly "slamming" the torque wrench, especially when using a ratcheting wrench, you can easily tighten beyond the target value.
By avoiding the use of an air wrench and following correct tightening procedures, you'Il avoid damage to the wheel and will greatly minimize the chance of a comeback for a vibration complaint. Overtightening or uneven tightening can easily cause hub/rotor distortion, which will result in brake rotor distortion.
Following the initial installation, it's advisable to check and retorque all wheel fasteners after the vehicle has been driven 25 to 50 miles. If the technician cannot perform this initial drive, make a point of instructing the customer to bring the vehicle back to the shop for a retorque.
Wheels are designed to center onto the vehicle hubs by one of two methods-lugcentricity or hubcentricity. A lugcentric wheel relies on centering via the fastener locations only. As the lugnuts (or wheel bolts) are tightened, the wheel is centered onto the hub. This requires precise location of both wheel bolt holes and the fastener locations on the hub. A hubcentric wheel is centered onto the hub via the fit of the wheel center hole at the hub face. The hub face will feature a center lip that engages into a recess on the wheel's center hole. Hubcentric designs more precisely locate the wheel onto the hub, to minimize the chance for installed radial runout.
In some cases, a hubcentric ring adapter is used to attain a proper fit, since the wheels at hand may feature a larger center hole. This makes the wheel adaptable to various hub center fitments, by simply choosing the correct-width adapter rings. It's possible that an old adapter ring has stuck to the hub. If this ring is not the correct size for the wheel, the wheel may not be able to seat flush against the hub (if the new wheels are already sized for the OE hub without a ring, or if the new wheels use a new ring). Always check the hub face flange diameter and the diameter of the wheel s mounting facehole to make sure they match before attempting to install the wheels.
The wheel must fit flush against the hub and be centered on it. If the wheel requires rings and none are used, you'll have an off-center installation. If old rings are stuck to the hub, but the new wheels don't need them, or if you try to double-up old rings that are stuck to the hub and new rings on the wheels, the wheels won't mate flush to the hub, which will cause severe axial runout. Always check carefully.
If your wheels include either aluminum or plastic hubcentric ring adapters, be sure to use them. Even if you feel that the fasteners alone will center the wheel, the rings provide a closer-tolerance fit to the hub center and will allow you to better center the wheel during tightening.
Before a vehicle leaves the shop with a newly installed set of custom wheels, do the customer a favor. Place one wheels set of OE fasteners in a resealable plastic bag and store them in the vehicle (in the tool kit, next to the spare tire or jack, etc.). If the customer ever needs to install the OE spare in an emergency, he'll have the correct fasteners, since the fasteners that are used with the aftermarket wheels may differ in length or style from OE. Also, the OE lug wrench might not fit the new fasteners, as the hex size may differ from OE.
If the new wheels' fastener hex size differs from the OE (for example, maybe the OE nuts require a 19mm wrench, but the new fasteners might require an 18mm or [fraction eleven-sixteenth]-in, wrench), be sure to also include an appropriatesized socket and breaker bar to allow the aftermarket wheel to be removed during a roadside tire change. At least make the customer aware of this, and offer the option of allowing him to purchase an appropriate socket and breaker bar, or at least tell the customer that he'll need these tools. Otherwise, the customer may be stuck at the side of a highway with no way to remove the aftermarket wheel.
And finally, before a vehicle leaves the shop, take a few extra minutes to clean the wheels and tires. Remember, the custom wheel customer is interested in appearance. Wipe off any fingerprints, smudges, etc., being careful not to scratch the wheel finish.
TIRE MATCH MOUNTING & CUSTOM WHEEL HANDLING
Mavrigian, Mike (is the author)
Some of the most common types of work done on performance vehicles involve the wheels and tires. This overview of tire and wheel-handling procedures provides information you'll need to keep your customers rolling smooth and straight.
Adding performance vehicle owners to your customer list can give a huge boost to your shop's bottom line. These owners may be demanding-even picky-but they'll pay well to get the job done exactly the way they want it.
Some of the most common types of work done on performance vehicles involve the wheels and/or tires. The wheels are one of the most visible parts of a vehicle, so any work done on them must be top-notch-meaning clean, pretty and accurate.
Custom wheel service can be broken down into two primary topics, essentially-tire match mounting and custom wheel handling. Since you'll never mount a wheel without a tire, we'll cover the ins and outs of tire match mounting first.
What Is Match Mounting?
Match mounting involves positioning the tire onto the wheel to minimize or eliminate thefinal combination of radial force variation and/or imbalance (radial force variation is explained later in this article). One match mounting approach involves aligning the tire's point of maximum radial force variation (its high spot) to the wheel's radial low spot (where the wheel's radial runout is the lowest). This is called the Uniformity Method. The other approach involves simply aligning the tire's lightest balance point to the wheel's heaviest balance point, called the Weight Method.
OE tire suppliers are required to mark a tire's radial runout high point, and OE wheel makers are required to mark a wheel's radial runout low point. This makes it easy for the OEMs to match-mount tires to wheels from a radial force variation standpoint during production. In some cases, these marks are made with paint dots that help service technicians remount tires down the road. However, sometimes these marks are made using temporary stickers, which either fall off or are removed after mounting. This leaves no readily visible reference marks for the tire technician for future service.
If a tire does feature color dots on the sidewall, one or two dots may be used. A red dot indicates the tire's radial runout high point. A yellow dot indicates the tire's point of least weight, from a balance standpoint.
For decades, it was common practice in the aftermarket to mount a tire so its red dot aligned with the wheel's valve stem, since the valve stem area was normally assumed to be the wheel's lowest point of radial runout. Aligning the tires high point to the wheel's low point (theoretically) reduces or eliminates the chance of developing a radial force variation (RFV) in the tire/wheel assembly.' RFV (again, an issue of runout, not imbalance) can cause a vibration that might be mistakenly diagnosed as an imbalance problem.
Times change. With the advent of styled custom wheels, the valve stem location may no longer indicate the wheel's low radial runout spot. In other words, it may no longer be viable to assume that aligning a tire's.red dot to the wheel's valve stem will address any potential RFV issues.
Consequently, a procedure that was once easy has now become complicated. The only way to accurately matchmount a tire to a wheel is to actually measure tire and wheel runout. The end goal remains the same: to align the tire's high point to the wheel's low point. The wheel itself can be easily checked for radial runout by mounting it to a hub and slowly rotating it while monitoring the rim edge with a rigidly mounted dial gauge. However, the only acceptable method to check the assembled tire/wheel package for radial uniformity under load is to use a state-of-the-art wheel balancing machine that features a load-roller that applies road-simulated load to the inflated tire. Such a machine will not only check for dynamic balance but will also locate the tire's high spot. If this high spot doesn't correlate to the wheel's low spot, the machine will let you know where to relocate the tire on the wheel to minirnize RFV
If you don't have access to a roadwheel type of balancing machine, and you don't know where a wheel's lowest radial runout spot is located, you can default to using the Weight Method, which involves aligning the tire's yellow dot to the wheel's valve stem.
As you can see, tire/wheel match mounting isn't a cut-and-dried method. Your approach to match mounting will depend on several variables:
* whether the tire is runout- and weight-matched,
* whether the wheels low runout spot can be determined, and
* whether you have access to a loadapplying balancing machine.
Regardless of the specific approach you take, it's important to understand that "stacked-up" runout and imbalance conditions can be addressed. Of course, once tire matching has been accomplished, the mounted package must then be checked and corrected for dynamic balance.
There are two types of radial runout -static and dynamic. Static runout, as we noted earlier, refers to the high spot of the tire, a physical characteristic that can be measured with no load placed on the tire. Radial force variation, however, refers to a dynamic runout condition, which occurs only when the tire runs at speed, under load, due to variations in construction stiffness.
Radial force variation is so named because the radius of the tire varies according to vehicle speed and load. Of course, any tire, because of its pliability, will vary slightly in radius at the load spot during operation. Although a "radial force" might be the result of a runout area pronounced enough to affect the tires impact on the road, a radial "force variation" may occur if the tire has appreciably different "soft" spots and "stiff spots in the carcass and/or tread or in the sidewall construction. Given the precise quality control processes used by todays tire makers, it's rare that a force variation problem will occur. But when it does, it can be a tricky demon to chase.
Even though no problems may be found as the tire rotates on the balancer, when the tire experiences a load, the transition of the harder and softer sections of the tire may create a series of harmonic vibrations as the various sections of the tire contact and leave the road surface. Depending on conditions, this harmonic may occur once per tire revolution, or in a series of multiple vibrations per revolution. It's possible that this phenomenon may vary according to changes in tire pressure, vehicle speed, individual tire load and road surface conditions, all of which may serve to reduce and/or amplify the vibration problem. In other words, the vibration the driver feels may not occur at any one rate of speed, or on any particular road surface, because the problem may appear only under a specific combination of these variables.
If a tire/wheel will not balance properly, or if a vibration exists after a successful balance job, don't automatically blame the tire. If you haven't checked the hub and wheel for runout, you may be jumping to conclusions. If, however, all balance, static runout and chassis parts variables have been exhausted, then it may be time to suspect a radial force variation problem.
To check for and attempt to actually verify a dynamic radial runout condition, a spin-balancer with a built-in load roller is recommended. This type of balance machine places a load (which attempts to simulate road load) onto the tire as it spins, while monitoring and recording variances of runout. If load variation is found, it may be corrected to an acceptable level via balancing weights. In extreme cases, it may verify that the tire should be replaced.
A minimum range of between .3 and .5 oz. (7 to 14 grams) of imbalance is usually enough for the average motorist to notice an imbalance-induced vibration. If a vehicle is sensitive enough to exhibit noticeable vibration at only .3 to .5 oz. of imbalance, that same amount of vibration may be present with as little as 10 to 15 lbs. of radial force variation, which (although hard to believe) can be caused by as little as .010 to .015 in. of loaded radial runout. Using this as an example, it's easy to see how loaded runout can dramatically affect vibration. In other words, a little bit of "loaded" tire runout variance can produce a notable impact on operating smoothness or harshness.
Handling Custom Wheels
It s extremely important to pay attention to wheel fastener seat styles. Make sure you use the correct style of wheel nut or bolt specified for the custom wheels at hand. Installing the incorrect seat style can damage the wheel bolt hole seats; at worst, it can result in the fasteners loosening on the road, with the wheels disconnecting from the hubs.
The seat refers to the actual contact area between the fastener's head and the wheel. The seat style of the fastener must match the seat style featured on the wheel. If the wrong seat style is used, the wheel simply wul not be fastened to the hub correctly. If the fastener seat style does not match that of the wheel, you'll likely damage the wheel finish and, more importantly, the wheel will eventually loosen and wobble as it moves in relation to the hub.
Seat styles most commonly found include radius, conical and flat ("mag"). These terms refer to the shape of the seat (where the fastener contacts the entry of the fastener hole in the wheel).
Radius seats, also referred to as ball seats, feature a ball shape that mates into a wheel's female radiused ball relief at the wheel's mounting hole.
Conical seats are also called cone seats or tapered seats. This seat style features an angled seat wall. The fastener features a male cone seat, the wheel a female cone entry hole. The most common seat taper angle is 60°.
A mag wheel nut features a flat contact patch at the wheel (and usually a thick flat washer). A mag-style nut may also feature a smooth outer-walled extended shank that helps center the wheel on a lugcentric design, as the shank enters the wheels bolt hole and serves as a guide pin to center the wheel's hole over the wheel stud. Using a capped nut (where the threads do not extend all the way through the nut) may make it difficult to be certain that the stud isn't bottoming out inside the nut. This is why it's important to pay attention to thread engagement length. At a minimum, the nut must engage onto the stud at a depth equal to the stud diameter. For example, if the stud diameter is 12mm, the nut must thread onto the stud by at least 12mm of depth. Also, make sure the stud does not bottom out inside the nut. If it does, it will be impossible to achieve full clamping load.
When it comes to torquing the fasteners, make sure the threads are clean and free of dirt, grease, grit, etc. If burrs or flat spots are found, replace the fastener (both stud and nut). Fasteners are intended to stretch slightly when fully tightened to specification. With regard to automotive wheels, this creates the correct preload required to secure the wheel to the hub.
If the wheel fasteners are undertightened, they'll eventually loosen, resulting in the wheel being damaged or actually coming off the vehicle. If the fasteners are tightened excessively, the wheel stud or bolt can permanently stretch, fatiguing beyond its designed elastic range. Overtightening also can result in fastener failure or, at the very least, in great difficulty during future removal. Especially with todays lightweight alloy wheels and sometimes light (and thin) rotor hats, severe vibrations under braking can occur if wheels are improperly or unevenly tightened.
The only way to ensure correct clamping loads is by tightening all wheel fasteners with a properly calibrated torque wrench. Every custom wheel should be installed by tightening the fasteners with a torque wrench only no exceptions. Using a torque wrench is more time-consuming than using an impact gun, but the owner of a set of custom wheels expects the installation to be performed correctly.
This brings us to the subject of impact wrenches and torque sticks. Torque sticks are basically little torsion bars with a square drive at one end and a hex socket at the opposite end. In theory, a torque stick should begin to twist (and thereby stop rotating the fastener) when a specified torque limit is reached. While the use of such a torque-limiting tool is better than nothing, the best and only proper method is to tighten all wheel fasteners with a hand-held torque wrench. Never use an impact wrench to tighten custom wheel fasteners.
Always install any wheel, regardless of what it's made of, by tightening the fasteners in a crisscross pattern to provide even clamping loads. Uneven tightening can easily result in a distorted hub or wheel, leading to vibration and brake pedal bounce complaints.
Pay attention to torque value accuracy. When you do use a torque wrench, make the final pulls slowly and carefully, creeping up onto the final value, or "click." By abruptly "slamming" the torque wrench, especially when using a ratcheting wrench, you can easily tighten beyond the target value.
By avoiding the use of an air wrench and following correct tightening procedures, you'Il avoid damage to the wheel and will greatly minimize the chance of a comeback for a vibration complaint. Overtightening or uneven tightening can easily cause hub/rotor distortion, which will result in brake rotor distortion.
Following the initial installation, it's advisable to check and retorque all wheel fasteners after the vehicle has been driven 25 to 50 miles. If the technician cannot perform this initial drive, make a point of instructing the customer to bring the vehicle back to the shop for a retorque.
Wheels are designed to center onto the vehicle hubs by one of two methods-lugcentricity or hubcentricity. A lugcentric wheel relies on centering via the fastener locations only. As the lugnuts (or wheel bolts) are tightened, the wheel is centered onto the hub. This requires precise location of both wheel bolt holes and the fastener locations on the hub. A hubcentric wheel is centered onto the hub via the fit of the wheel center hole at the hub face. The hub face will feature a center lip that engages into a recess on the wheel's center hole. Hubcentric designs more precisely locate the wheel onto the hub, to minimize the chance for installed radial runout.
In some cases, a hubcentric ring adapter is used to attain a proper fit, since the wheels at hand may feature a larger center hole. This makes the wheel adaptable to various hub center fitments, by simply choosing the correct-width adapter rings. It's possible that an old adapter ring has stuck to the hub. If this ring is not the correct size for the wheel, the wheel may not be able to seat flush against the hub (if the new wheels are already sized for the OE hub without a ring, or if the new wheels use a new ring). Always check the hub face flange diameter and the diameter of the wheel s mounting facehole to make sure they match before attempting to install the wheels.
The wheel must fit flush against the hub and be centered on it. If the wheel requires rings and none are used, you'll have an off-center installation. If old rings are stuck to the hub, but the new wheels don't need them, or if you try to double-up old rings that are stuck to the hub and new rings on the wheels, the wheels won't mate flush to the hub, which will cause severe axial runout. Always check carefully.
If your wheels include either aluminum or plastic hubcentric ring adapters, be sure to use them. Even if you feel that the fasteners alone will center the wheel, the rings provide a closer-tolerance fit to the hub center and will allow you to better center the wheel during tightening.
Before a vehicle leaves the shop with a newly installed set of custom wheels, do the customer a favor. Place one wheels set of OE fasteners in a resealable plastic bag and store them in the vehicle (in the tool kit, next to the spare tire or jack, etc.). If the customer ever needs to install the OE spare in an emergency, he'll have the correct fasteners, since the fasteners that are used with the aftermarket wheels may differ in length or style from OE. Also, the OE lug wrench might not fit the new fasteners, as the hex size may differ from OE.
If the new wheels' fastener hex size differs from the OE (for example, maybe the OE nuts require a 19mm wrench, but the new fasteners might require an 18mm or [fraction eleven-sixteenth]-in, wrench), be sure to also include an appropriatesized socket and breaker bar to allow the aftermarket wheel to be removed during a roadside tire change. At least make the customer aware of this, and offer the option of allowing him to purchase an appropriate socket and breaker bar, or at least tell the customer that he'll need these tools. Otherwise, the customer may be stuck at the side of a highway with no way to remove the aftermarket wheel.
And finally, before a vehicle leaves the shop, take a few extra minutes to clean the wheels and tires. Remember, the custom wheel customer is interested in appearance. Wipe off any fingerprints, smudges, etc., being careful not to scratch the wheel finish.
Jun 15, 2008, 12:57 PM
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i have the same tire and work at a shop so i did them myself. all you have to do is mount them on the rim in the direction u want them to go. then put them on the balancer/road force machine. if the road force number is high (over 20) the machine will have you make a mark on the tire and on the rim and match those up to bring the road force down for a smoother ride. its that simple. mine rides like a brand new car
