Ultra-high performance tire sizes are now the norm on many sport sedans, SUVs and crossover vehicles. Even luxury sedans come with UHP tires.
o compete in this market, you must have high-quality equipment that can handle 22-inch and larger wheels and tires without damage or come-backs. Stiff sidewalls, hard treads and different drop centers all combine to make mounting and balancing them a challenge.
There are two parts to the mounting and balancing process that must be considered. The first is the equipment itself; the second is the time and motions required of the tire tech by the equipment. The best equipment in the world will not make you money if your staff does not know how to use it properly.
When you are looking at purchasing new equipment, take your watch with you and time the entire process. Also, look at the work required by the tire tech during the man/machine interface. Good equipment must be user-friendly and deliver consistent results. It is probably best to make your buying decision based on the user interface over any other bells and whistles.
Also investigate whether or not the equipment can be upgraded as new technology and functions are developed.
You can review the specifications of each brand and model, but stand back and consider the process, not just the result. Analyzing the ease with which your technicians will interface with the equipment (especially given the high rate of turnover in these positions) should be a key driver in making your purchase decision.
A tire changer with power assist, rim and tire protection features, and adequate power is important. Most UHP tires have low-profile or ultra-low profile sidewalls, making the tire extremely inflexible. A tire changer with power assist features allows one person to press and hold the tire into the rim drop-center.
Also, rims on high performance vehicles are usually attractive, but also delicate, due to the fact that they are made of thinner, lightweight materials.
These expensive wheels need every protection possible in order to be handled without damage. A standard, no-frills tire changer usually does not include the type of protectors necessary to do this well.
Employee perspective
When evaluating a UHP tire changer from the employee perspective, consider the following:
• The mount/demount process steps for each machine. To what extent does the process for servicing UHP assemblies differ from the way your technicians service conventional tires and wheels?
The lesser the difference, the shorter the learning curve for your technicians, the smaller the chance for errors, and the sooner the machine begins to pay for itself.
• Are the controls for the various “helper” devices (powered drop-center assist arms, wheel lifts, etc.) located at the device, or are they located elsewhere on the machine (i.e., operated remotely)? Controls located at the point of use are much more intuitive and easy to use, and keep the technician focused on proper tire service procedures.
• The general ergonomics of the machine. Look specifically for wasted motion (i.e., walking from one side of the machine to the other and back) to perform different steps in the mount/demount process or otherwise reach or locate a tool or control.
Needless steps are a prime example of process waste, and should be minimized to maintain productivity and bay turns.
You must also consider the following three features:
1. User interface. How well does the machine communicate with the technician? Does it prompt the technician to perform the proper process steps (data entry, weight placement, etc.) and walk him or her through the balancing process? This feature will greatly reduce the learning curve for new technicians.
2. Error recognition and/or error-proofing. Does the machine recognize and report, or better yet, prevent, potential errors (improper data entry, a loose hub nut or excess residual imbalance)?
Such capabilities reduce process variation and opportunities for error, which will minimize the chances of a costly comeback — which, coincidentally, are more likely on large, low-profile, stiff-sidewall applications.
3. Economies of motion. Does the machine cut down on wasted motion, especially in data entry?
By keeping these technician-friendly criteria top-of-mind, you will end up with equipment that not only handles the myriad of application challenges presented by UHP applications, but also is extremely easy and intuitive to use — equipment that everyone in the shop can operate, not just the select one or two.
Machine perspective
Just when you think passenger car and light truck and SUV wheels can’t get any bigger, they do.
Thirty inch diameter wheels, and the UHP tires to match, although not commonplace, have appeared in the aftermarket.
And now many OEMs are offering UHP tire and wheel upgrade packages — many up to 22-inch in diameter — in order to grab their fair share of the multi-billion-dollar custom wheel market.
The issue you’re dealing with is, of course, a fixed amount of wheel well space. As the wheels get bigger, the aspect ratios of the accompanying tires get smaller.
This means thicker, stiffer sidewalls that are more challenging and time-consuming to mount and demount, and more prone to vibration.
To compound matters, today’s uni-body vehicles are considerably lighter and have much stiffer suspension systems than they did just 10 years ago. Gone are the generous cushions and dampeners that typified the suspensions of yesteryear.
Quite simply, today’s vehicles are just more sensitive to vibration than they used to be.
But in response to overwhelming demand and profit opportunity, the industry continues to equip these vehicles with bigger, heavier and stiffer UHP tire and wheel assemblies.
The result is a dramatic increase in road feel and unsprung weight — that is, weight not supported by the vehicle’s suspension system — which, aside from various effects on vehicle performance, can lead to a harsher ride.
These factors all critically impact the machine component of your tire service process.
The good news is that by casting a critical eye toward a few key machine attributes, you can mitigate many of these challenges with your equipment selection.
When evaluating a tire changer that will be used to mount UHP tires, don’t forget to consider the following:
• There is a greater risk of sidewall damage and bead distortion when mounting/demounting UHP tires. “Articulating powered helper devices” designed to keep the bead in the drop center — a critical requirement in the mount/demount process — are virtually required to service UHP applications. In fact, they are critical when mounting low-profile UHP tires on custom wheels that have shallow and/or gently sloping drop centers. Such wheel designs are, unfortunately, commonplace in the aftermarket.
• General upgradeability. Can you add larger capacity clamps at a later date? One trip to the Specialty Equipment Market Association (SEMA) Show will convince you that there’s always something bigger and badder on the horizon in the aftermarket wheel industry.
Can the tire changer be equipped with additional devices or accessories to handle evolving run-flat designs? The ability to upgrade will protect your investment, keep your tire service process capable, and safeguard your ability to provide best-in-class service to your customers.
• Torque isn’t just for lug nuts anymore. The torque generated by a tire changer’s motor (specifically the start-up torque) will determine your likelihood of stalling or jamming the machine when attempting to mount a very stiff top bead and your ability to successfully back out of it if that happens.
Of course, using the proper method — adequate lubrication and allowing the bead to relax during the mounting process — will prevent most of these occurrences.
Aside from the fact that large UHP assemblies tend to require more corrective weight than their smaller cousins, the main issue you’ll encounter when balancing these tire and wheel combinations is the need for finer, more accurate balancing and vibration control.
When evaluating a wheel balancer for your UHP needs, follow these steps:
1. Pay special attention to how each balancer deals with static imbalance. Static vibration (the “bounce” versus the dynamic sensation of “wobble”) is what drives most vibration-related comebacks.
Some balancers will eliminate static imbalance at the expense of a large dynamic residual. Others pay no special attention to static at all, focusing solely on dynamic imbalance. And there are those that deliver the best of both worlds — simultaneous minimization of static and dynamic imbalances.
For UHP applications, which are more prone to vibration by nature, your balancing process cannot afford trade-offs.
2. Know how to explain the difference between balance problems and force variation problems.
3. Give some thought to investing in a diagnostic balancer. These machines deliver all the balancing features required by today’s power users: direct adhesive weight placement, behind-the-spoke balancing, on-board inflation, real- time graphics and on-board training. They also diagnose other vibration generators that are common to tire and wheel assemblies, such as excess radial runout, excess lateral runout, and excess residual imbalance.
Although these conditions are only responsible for 10% of vibration-related comebacks in general, they are especially troublesome on large, low-profile UHP assemblies.
Also pay special attention to the machine’s incremental cycle time for diagnostics.
This can vary greatly between equipment manufacturers. Quicker diagnostic cycle times not only protect your productivity, but also ensure that your technicians actually use the diagnostic process on every balance, rather than turn it off for the sake of speed, which would defeat the purpose of your investment!
‘Method’ perspective
You can buy the best tire service equipment on the market today, but if you don’t establish and enforce proper mounting and balancing methods, your tire service process will undoubtedly suffer.
Since UHP tires are usually on a performance vehicle, a precise dynamic balance is critical.
You simply should not try to speed through a balance on UHP tires. I don’t recommend using a “weight saver” type of program on UHP tires. Weight saver programs use parameters that are simply not precise enough for UHP fitments.
Also very important is extremely precise mounting of the wheel assembly to the balancer.
Smart tire techs know that “lube is your friend.” Insufficient lubrication can result in bead distortion or other tire damage. Conversely, excessive lube or an improper mixture could result in tire slippage.
Using the proper amount and type of lubricant for UHP applications is a key factor in reducing variation in the mounting process. Be sure to not only apply it to the tire bead, but also to the bead seat and drop-center areas of the rim.
Successful techs also know that sometimes you have to slow down to speed up. Take your time when servicing UHP tires. Check for tire pressure monitoring system sensors. Let the top bead relax a little during the mounting process.
Use all the helper devices at your disposal. The result will be consistent output of quality work and less variation in your tire service process.
If you’ve invested in a tire changer with a wheel lift, use it. I know, I can hear it already: “I’m faster than that lift! My technicians should be able to lift the assembly onto the machine.”
OK, let’s suppose that’s all true. Research shows that most wheel damage occurs while mounting the wheel on the machine.
Encouraging (if not enforcing) the use of your wheel lift will save you money on damaged wheels, avoid embarrassing customer situations, and help error-proof your mount/demount process. Plus, it will leave your technicians fresher toward the end of the day, which should improve their productivity.
Balancing
The goal when balancing a UHP tire and wheel package is straightforward — to provide your customers with a vibration-free ride on the first attempt.
First and foremost, you must be certain that you mount the tire and wheel assembly on the balancer in the exact same manner that it will be mounted back on the vehicle.
Consider this mathematical fact: A 16-inch diameter, seven-inch wide wheel mounted and balanced just .010 inch off-center on the balancer shaft will result in a .85 ounce static vibration when mounted back on the vehicle. And the balancer, which only can assume that you’ve centered it properly, will gleefully show you zeros.
Process errors such as this one are easy to make and are responsible for upward of 60% of vibration-related tire service comebacks. The good news is that they are easy to avoid.
First, monitor the condition of your mounting cones and replace them when they begin to appear nicked or worn. This will remove cone condition as a source of process variation.
Second, invest in a set of mounting adapters such as pin plates (also known as flange plates) or fixed finger plates.
These adapters engage the wheel in its lug holes. When used in conjunction with mounting cones, they provide an almost error-free method for mounting.
For hub centric wheels (nearly all OE wheels are hub centric), the adapters distribute the clamping pressure equally around the center hole — just like the lugs and lug nuts do on the vehicle — and ensure that the wheel ends up centered on the cone.
For lug centric wheels (most aftermarket wheels are lug centric) the wheels pre-center on the cone, and as you exert clamping force via the hub nut, final centering is achieved on the fingers of the adapter.
The result is, again, that the wheel will be balanced in the same way that it will be mounted back on the vehicle. More importantly, this process establishes a consistent, reliable process for mounting most any wheel on your balancer.
Of course, there are certain scenarios that require other, more specialized adapters.
Your equipment distributor should be able to help in this regard.
By considering the impact of your equipment purchases on your employees, and looking at UHP tire service from the equipment and method perspectives, you will be able to make more informed purchase decisions. Combine that with well-trained technicians, and your profits will increase. ■
