To many in the tire industry, TPMS is a four-letter acronym that is quickly becoming a four-letter word. That goes for retail dealers and, soon, consumers alike. But these people are only considering the hassles involved with servicing tire/wheel assemblies featuring these gizmos.
Look a little deeper, and you’ll see the potential for independent shops to be big losers in a massive technology shift they can’t control and can only hope to survive – unless they get significant help.
TPMS stands for “tire pressure monitoring system,” and most tire and auto industry observers and participants realize that TPMSs are here to stay – regardless of the confusing state of government regulations.
TPMSs are the result of a TREAD Act mandate requiring such devices on all new passenger vehicles. The TREAD Act stated that TPMS regs were to be in place by October 2003, but various fits and starts – including trips to federal court – have slowed the process.
As the most current regulations – issued this past April – stipulate, all passenger vehicles with a gross vehicle weight (GVW) under 10,000 pounds must be equipped with a TPMS that alerts the driver if one of the tires is 25% underinflated. As currently defined, the standard is being phased in, beginning with the new cars of 2006 – 20% were required to be in compliance by Oct. 5; 70% by Sept. 1, 2006; and 100% by Sept. 1, 2007 (model year 2008).
NHTSA’s original rule stated that automakers could use either “direct” or “indirect” systems (See sidebar below). A successful lawsuit by Public Citizen and other consumer groups forced NHTSA to change its mind, and a new proposal allowed for only direct systems, which are considered to be more precise.
Oddly, NHTSA changed its mind again, issuing final rules earlier this year that allow the rather questionable indirect systems to be used.
For automakers, indirect TPMSs are a matter of economics; they are far cheaper. Automakers can spend less money by installing indirect TPMSs on the two-thirds of vehicles that are currently equipped with anti-lock brakes and put direct TPMSs on the others.
Inside the Lawsuit
The main issue now before the federal appeals court is NHTSA’s seemingly arbitrary alert threshold of 25 percent below the vehicle manufacturer’s recommended inflation pressure. The tire industry has been adamant in wanting no less than a 20% underinflation threshold. Specifically, the plaintiffs believe the TPMS alert’s trigger point should be tied to a vehicle’s gross axle weight rating (GAWR) and/or each vehicle’s “real weight.” That would mean a low-pressure warning would trigger at one to two psi below the recommended cold inflation pressure or at an inflation level at which the tires can no longer carry the vehicle weight safely, whichever is higher.
In addition, the group also questions NHTSA’s ruling that OE-installed TPMSs are not required to work with replacement tires and that TPMSs need only to function after a vehicle is driven between 50 and 100 kph continuously for 20 minutes.
Importantly for dealers – and any independent shop that services tires – the group also challenged NHTSA on the availability of sensor repair and recalibration information to the aftermarket.
Just weeks ago, NHTSA denied a separate request by SEMA to require automakers to provide TPMS service information to independent shops, and a separate request that OE TPMSs allow recalibration to accommodate tires with different recommended inflation pressures.
That means that – at least for now – automakers control the TPMS table. Independents who want reinstallation and recalibration procedures for a particular make and model will have to track it down themselves and probably pay for such necessary information.
Heart of the Matter
Because of the delay and uncertainty about the final version of the regulations and the lack of subsequent helpful information, tire dealers and specialty performance shops that sell and service tires on customer wheels are ill prepared to deal with TPMS.
Dozens of OE systems are already on the street, and hundreds of horror tales have been told of sensors that have been broken during ‘routine’ mounts/demounts and complicated recalibrations after ‘routine’ tire rotations. With the cost of replacement TPMSs in the $200-to-$300 range, and 100% compliance likely just a few short years away, there will be no such thing as simple tire service anymore.
Because the OEMs will help their dealers first, and because getting necessary service information and tools remains difficult and costly for service facilities, it is a legitimate fear that new-car dealers will make the most hay out of TPMS.
As the auto industry has an inherent head start on tool inventory, training, expertise, etc., and the all-important service issue, the tire industry is appropriately asking itself a few poignant questions:
What tools – including hardware, software and training – will we need to ensure that we can handle our customers’ needs? And, on behalf of the proactive participants, how can we parlay this mandate into new business?
Fortunately for the aftermarket service industry, some of the tools already exist, and training programs with software and manuals are being developed by several groups, including Delphi, AutoWare (direct and indirect systems), Schrader Electronics, SmartTire Systems, Alldata, Bridgestone/Firestone, Mitchell1 and TIA.
One of the main reasons that training is so critical for servicing TPMSs is that if a sensor is damaged during a tire change, it will likely cost the shop $100 or more just to replace it, plus the time and cost involved in finding and installing a replacement sensor.
Shops Seek Help Now
While training is growing and being addressed bit by bit, another immediate concern for the aftermarket is trying to find replacement parts for those 50 to 60 different systems already in existence.
“Our guys are getting more familiar with (TPMS), but most suppliers are not carrying the valve stems you need,” said Jay Ehrenfried, owner of Golden Gate Goodyear in Mayfield Heights, Ohio. “Right now, we have to buy them from auto dealers – for Cadillacs and top luxury cars like Lexus, etc.
“If the system is damaged, that’s one thing. But, when you have to go out and find the replacement parts, well, that’s another problem.
“There is a real limited supply of replacement valves, and they cost about $150 for one. Valve stems used to be a profit center for me,” he says. “These have leaked frequently, and, recently, when I had to replace tires on a Nissan SUV, I had to order a valve from California.”
In addition, valve caps, stems, cores and O-rings are other scarce parts.
“The cores are not removable They are aluminum, and you can’t put a steel valve core back into them because it will weld the core inside,” said Ehrenfried’s service manager, Scott McPherson. “We also have trouble with valve caps because they usually require an O-ring. But, the things that deteriorate are the O-rings that seal it into the wheel.”
O-rings are found on each side of the valve stem – inside and outside of the wheel – and under the valve cap, to prevent leaks. Finding a source for those is a huge concern.
Servicing TPMS Systems
When a TPMS-equipped vehicle reaches your service or tire techs, do they know what to do? While there are as many ways to skin this cat as there are TPMSs, here are some practical tips from Craig J. Knarich, owner/operator of Pit Crew Tire in Palm Harbor, FL, on how to handle valve-stem TPMS units. This is not intended to be a step-by-step procedure to fit every application; these are just some general guidelines to consider when approaching TPMS replacement.
Put the car on the lift. “It sounds stupid, but you’d be surprised how many don’t start with this step,” said Knarich.
There is a small aluminum tool called a three-purpose tool available through Myers Tire Supply (part number 27117) or American Tire Distributors (which calls it a two-sided valve tool, part number 435176020). It’s just like a valve cap and fits over the stem. This device is used to take the air out of the tires – safely and securely – without removing the valve core. It screws onto the valve stem and depresses the core, removing the air safely.
After deflation, remove the valve tool. Then, place the assembly onto the tire changer’s side shovel.
Do not remove the TPMS yet. This is another no-brainer, as losing or forgetting the rubber O-rings and washers is very easy to do, but it can’t be overstated. You’ll have to re-torque the TPMS in inch-pounds. And, how many dealers have an inch-pound torque wrench in their shop? Just leave it on.
Break the tire down. If you are using a side shovel, one of the most common machines in tire shops, make sure that you position the valve stem (TPMS) 180 degrees away from the side shovel.
On the changer, if your bar is going in at the 12 o’clock position on the demount head, put the TPMS at 2 o’clock. Then, rotate the turntable counter clockwise until the TPMS meets the demount head and bar at 12 o’clock. Then, proceed clockwise until the top bead comes up.
Repeat Step 6 for the bottom bead. If you do this, it will never come in contact with the TPMS unit. Prior to demounting, Knarich highly recommends generously lubing the wheel and tire (he prefers white paste lube) using a large paste brush. This, too, prevents harsh contact on the TPMS as the tire comes off, allowing the bead to go over the unit instead of snapping it off. Minor lube contact to the TPMS is OK, but try to avoid it if possible.
When mounting a tire, the best position for the TPMS is between 3 o’clock and 5 o’clock. The TPMS has to be ahead of the tire by about two to three inches in the drop center. This depends on how aggressive you are about pre-loading the tire into the drop center and on the equipment you are using. Sometimes, aggressive pre-loading is advantageous, Knarich said, as it may prevent slippage of the tire on the rim during mounting. This also helps the complete mounting of both beads on the wheel (valve stem area) in the same area of the mounting head.
Last, but not least, is tire inflation. Easy, you say? Sometimes not. With low-profile tires, it can be a challenge to hand-rotate a tire on the wheel – even without a TPMS – to get up over the safety bead. It can be more difficult on EH2 or AH2 beads and is a common problem with some European cars. You have to get over the safety bead on the wheel because the air inflation hole on most TPMSs is on the side, not on the bottom.
Types of Tire Pressure Monitoring Systems
Indirect: The majority of current systems in use are indirect. Linked to existing anti-lock brake systems, indirect TPMSs don’t measure tire pressure; they calculate (some would say “guesstimate”) air pressure using sophisticated algorithms to infer when a specific level of underinflation has been reached. How? Software bases its pressure calculation on the principle that an underinflated tire will have a smaller radius than one properly inflated; therefore, an underinflated tire will produce more revolutions per mile than a properly inflated unit. Indirect systems compare one tire’s RPM to the others which is OK if just one tire is affected. But these systems give false readings if tires on the same end of the vehicle or all the tires are underinflated.
Direct: These systems feature a sensor – mounted at the drop center of the wheel, applied to the inner liner or as part of the valve stem assembly – in each wheel/tire assembly. The sensor sends live inflation pressure data to a receiver, normally located in the wheel well. A valve-stem TPMS sensor weighs approximately 1.4 ounces, while a normal rubber valve stem weighs half an ounce. The obvious concern involves balancing.