Top 10 things you should know about UHP tires and TPMS
Immediately following my third full-time summer of changing tires, I started my freshman year of college. That was in 1985.
Shortly after the beginning of my first semester, I was introduced to “The Late Show with David Letterman” by my buddies in the dorm and was hooked immediately. What was I doing up that late on a school night? Don’t ask.
So when I received tickets to a live taping of the show in Chicago during my senior year, I skipped class to attend. My neighbor and I stood in line for hours, and then watched Letterman do his thing for exactly 60 minutes and walk off the stage. It was the fastest hour of my life.
While I can’t say I remember his first “Top Ten” list back in ’85, I can say I’ve enjoyed thousands of them since then, including that one day in person.
Letterman wasn’t the first person to rank things from one to 10 (or, in his case, 10 to one), but he was the first to make it cool.
When the editors of Modern Tire Dealer first asked me to address the top 10 things retailers should know about the relationship between ultra-high performance (UHP) tires and tire pressure monitoring systems (TPMS), I tried to summon my inner Letterman and come up with something clever and witty. Ultimately, however, I decided that I should leave the comedy to the professionals and stick to what I know.
So, from the home office in Nottingham, Md., here are my top 10 things everyone should know about UHP tires and TPMS.
10. Nitrogen will not improve TPMS sensor performance.
Sensor performance is based on a lot of things and nitrogen is not one of them. Before the nitrogen generator manufacturers start writing rebuttals, there are advantages to nitrogen inflation, among them the slower bleed rate so inflation pressure doesn’t need to be adjusted as often.
The benefits to TPMS are typically focused on the absence of moisture, with the assumption that dry air would enable the electronics to perform better and last longer. If the battery had an unlimited life (which it doesn’t), then there might be a slight possibility that dry nitrogen would result in a sensor that lasts longer. But sensor manufacturers have to test sensors under a multitude of conditions, and the minimal amount of moisture in even the worst air system shouldn’t be enough to negatively affect a sensor.
That doesn’t mean, however, that techs can leave standing water or excess bead lubricant inside a tire, as any substance (other than air) can possibly clog the port and damage the sensor.
9. Winter UHP tire and wheel packages are not required to include TPMS sensors.
The decision to ensure that the tire pressure monitoring systems remain operational after a custom tire and wheel fitment lies solely in the hands of the customer. Original equipment wheels are a different story, but many UHP customers do not want to take the chance of tearing a bead or destroying an expensive rim, so they opt for a set of winter tires and wheels.
Dealers should encourage the customer to make the investment in sensors simply because it makes sense to protect a $150 or $200 UHP winter tire with TPMS, but they cannot be forced to pay for new seal kits or new sensors. If customers opt out of the extra expense, then they must understand they are going to drive around all winter with the TPMS light illuminated — and the system won’t be monitoring those expensive winter tires.
That being said, it won’t keep a tire dealer out of court should an accident occur after installation, so retailers should contact their respective legal counsel or insurance carrier to determine if a waiver is necessary under these circumstances.
8. Aftermarket monitoring systems are available for UHP fitments that do not include an original equipment system.
The number of vehicles on the road that include an original equipment TPMS represents a small percentage of the overall vehicle population, so there are hundreds of thousands of UHP tires that are not being monitored. There are aftermarket systems currently on the market that utilize valve stem sensors and wireless receivers that can be mounted on the dashboard, some without the need to run wires to the vehicle for power.
7. It’s recommended, but isn’t necessary, to drop the sensor before unseating the beads or demounting a UHP tire.
When TPMS sensors first entered the market, a lot of people encouraged technicians to remove the hex nut prior to service, especially on UHP tires, and “drop” the sensor into the tire. The theory was that a sensor in the bottom of the tire couldn’t be broken when the beads were unseated or when the tire was demounted.
While this is undeniably true, it also requires the technician to replace the seal kit before mounting the tire. If a replacement kit is not available, this practice will cause more problems than it solves.
The best practice is to replace the rubber grommet and the hex nut every time a tire is replaced, but a simple puncture repair doesn’t necessitate a seal change on a relatively new tire that just had a kit change, so the tire can be serviced with the sensor in place.
There’s also the issue of cost and the customer’s willingness to pay more than double the price of a standard rubber snap-in valve stem every time a tire is serviced. If the customer refuses to pay, the dealer is forced to either eat the cost to minimize the liability or leave the valve stem in place throughout the process and note the customer refused new seal kits.
In a perfect world, everyone would pay for a new kit. In the real world, the recession makes every dollar important, even to UHP customers who wouldn’t blink an eye to such charges in the past.
6. When unseating the beads on a UHP tire with a TPMS sensor, make sure the shovel is clear of the sensor.
The bead breaking shovel on some tire machines will cause the assembly to move in toward the drop center of the rim as it is activated. If the sensor is located in this area, it may be damaged.
On UHP tires, it’s often necessary to apply force with the shovel in several places in order to completely unseat the beads. The key to success is to make sure the shovel is either opposite or 90 degrees from the sensor at all times.
Since UHP tires are often difficult to unseat, it may become necessary to apply force directly at the sensor. When this occurs, technicians must remember that a full stroke of the bead breaking shovel will damage the sensor, so a partial stroke is necessary when applying force over the sensor.
5. Bead depressers are a must when mounting the top bead.
Modern tire changing machines include the necessary attachments to ensure that the top bead stays in the drop center throughout the mounting process. When the bead slips out of the drop center, the bead toe probably will suffer the consequences.
Bead depressers can be manual and basically snap on to the rim flange or hydraulic with an arm or roller. Regardless, mounting a UHP tire is difficult enough, so the additional hazard of a TPMS sensor just increases the risk.
4. The weight of a TPMS sensor is enough to create an imbalanced assembly.
Tires and wheels are manufactured to be perfectly balanced, so adding a sensor that weighs anywhere from 1 to 1.5 ounces is going to have a negative effect on the rotating assembly. To make matters worse, more and more OE wheels are coming without an outboard rim flange, so retailers who are not equipped with advanced balancers or proficient with the use of tape weights should expect more ride complaints. Poorly trained technicians will just set the machine to static and apply a weight to the back flange.
If the goal is a perfectly balanced UHP tire and wheel assembly when the sensor is in place, then the retailer must invest in the right equipment and constant training. By utilizing the correct “pin-plate” and the advanced features of modern balancers, technicians easily can apply a tape weight to achieve static and dynamic balance. Properly balancing a UHP tire with a TPMS sensor, however, is going to take extra time.
3. Without proper bead lubrication, the question isn’t if UHP tires will be destroyed or TPMS sensors will stop working, but how many.
This is by far the most complicated statement in the countdown. I’ll start with the first of the two scenarios.
When the bead toe on a UHP tire, or any tire for that matter, is torn at the point where the polyester body cables are exposed, the tire is junk. It cannot be repaired or returned to service, and in many cases the culprit is associated with bead lubricant, or the lack thereof. It’s another one of those situations where the evidence is on the vehicle because a tire failure caused by a sidewall separation that started at the rip in the bead toe will not be difficult to find or prove.
Before a tech can “properly” lubricate a UHP tire, the lubricant itself must be “proper.” With that in mind, petroleum-based compounds are strictly forbidden, as are any lubricants that do not specifically identify tires or rubber on the container. Bead lubricants should be clearly marked, non-flammable, and kept as clean as possible.
In my opinion, liquid lubricants are best for demounting because it’s easier to make sure the entire bead is covered as well as the rim. And since the location of the TPMS sensor is vital during UHP tire demounting, it also may be a good idea to lubricate the back bead after unseating.
When it comes to mounting, my personal feeling is a paste lubricant works best. First, it doesn’t dry as fast as liquids, so when technicians are taking their time when mounting a UHP tire with a TPMS sensor, the lubricating properties are not diminishing due to evaporation. Second, it cannot puddle inside the tire, and therefore reduces the risk of clogging the port in the sensor. Finally, a paste bead lubricant allows the technician to lubricate the key surfaces of the rim without adding significant moisture to the inside of the tire.
Mounting a UHP tire on a rim with a TPMS sensor is a double-edge sword. Improper bead lubrication increases the risk of serious damage, especially when mounting the top bead. It’s one of those “walk and chew gum” things where technicians have to pay attention to the bead toe, making sure it isn’t being torn, and the position of the sensor so it won’t be damaged by the bead in the drop center.
The Rubber Manufacturers Association (RMA) released Tire Information Service Bulletin (TISB) Volume 43, Number 1 (available at www.rma.org) to address this. It advises technicians to lubricate the following areas: 1)The bead humps and bead seating surfaces on both sides of the rim. 2) Both tire beads from the molded rib on the lower sidewall to the bead toe. 3) The inside of the tire from the bead toe to at least an inch or two on the innerliner.
Applying bead lube to the inside of a tire is new for many technicians, but it is an accepted and approved method for mounting UHP tires without causing major damage to the bead toe. Again, moisture inside the tire is not beneficial to the tire or the tire pressure monitoring system, so it’s important for technicians to exercise caution when using bead lube on the innerliner.
2. When demounting UHP tires on rims with TPMS sensors, always start the process at the sensor.
It doesn’t matter if the TPMS sensor is attached to the valve stem or secured to the center of the rim with a metal band. If the sensor is under the demount/mount or “duck” head of the tire changing machine when the bead is pried over the rim flange, then the chances of damaging it are significantly reduced. Since the majority of TPMS assemblies utilize valve stem sensors, technicians need to remember that the valve stem must be positioned at the duck head for both the top and bottom beads.
1. Understanding the traction point is the key to mounting UHP tires on rims with TPMS sensors.
When mounting any tire on a single-piece rim, the location where the bead crosses the rim flange is called the traction point. When a TPMS sensor is either attached to the valve stem or secured to the drop center with a metal band, it must be slightly ahead of the traction point to ensure it cannot be damaged by the tire bead.
This is especially important when mounting the top bead, since it’s not uncommon for the rim to spin a little inside the tire. If the sensor spins too far forward, it may become damaged, so when the rim spins inside the tire, technicians should stop and determine if the sensor will contact the bead before they continue to mount the top bead.
There is no doubt that tire retailers are going to see more UHP tires on wheels that include TPMS sensors. The combined value of everything is typically measured in thousands of dollars, so paying attention to the details is more important than ever.
It’s going to take a well-equipped, highly trained and motivated workforce to take the necessary time to ensure the tires are demounted and mounted without damaging the beads or the sensor. If retailers follow my top 10 list, I’m positive that the number of problems associated with servicing UHP tires on TPMS-equipped vehicles will decrease. ■