Tow Car Tire Monitors

[rmcdonald]

I have a 2013 Chev. Sonic as tow car. I want to add external tire monitoring but vendors say you need metal valve stems. The car has factory monitors attached to the inside of the rubber valve stems. A tire dealer told me it is illegal to remove the factory system(federal law).

Has anyone found a solution for this problem?

[wolfe10]

rmcdonald,

Welcome to the FMCA Forum.

Contact one of the TPMS manufacturers such as Pressure Pro. A tire dealer who breaks down tires may also know. A third source if information would be a Chevy dealer. That question has to have come up before.

At least on our 2008 Ford with factory built in pressure monitors, it was NOT attached to the valve stem. When we got new tires, just had them use metal stems-- no big deal.

[desertdeals69]

I have a Prius which has rubber stems with senders. I use Tire Minder on it when I tow with the front on the dolly.

[Xplorer]

I tow a 2013 Sonic with external TST tpms sensors on rubber valve stems. (Clarification: the Motorhome has the metal chrome duallyvalves. I would not use the TST on rubber Motorhome valves.)

They have been on for a year without any problems.

The manufacturers internal tpms still functions as normal when driving the Sonic.

The external tst sensors on the Sonic are monitored from the Motorhome.

I was advised the rubber stems were not a problem. They have not been an issue for me. Your mileage may vary.

[wigginsjsr]

I had my rubber stems replaced with metal stems without a question. Had it done at Discount Tire.

[bizsmith@yahoo.com]

Rubber valve stems can be a problem. My sensors would loosen as I drove. You can get along by religiously checking and tightening the sensors every day. I replaced my rubber stems with metal. I still check them regularly but they have not loosened themselves since.

The ones that loosened with the rubber stems were always the ones on the right (passenger) side.

A caution with metal stems. The metal used tends to corrode more readily, so be sure to loosen the sensors periodically or you won't be able to remove them. I was cautioned about this by the Costco tire technician when I had the metal stems installed.

[wolfe10]

Before assuming that rubber valve stems are acceptable for TPMS sensors, check with the manufacturer. The biggest problem I see is the flexing of the rubber caused by the .75 ounce or so weight of the sensors on the end of the valve stem. They were not designed for that.

[sandyhepburn]

Before assuming that rubber valve stems are acceptable for TPMS sensors, check with the manufacturer. The biggest problem I see is the flexing of the rubber caused by the .75 ounce or so weight of the sensors on the end of the valve stem. They were not designed for that.

According to TST literature the flow-through sensors they supply with their 507 system weigh in at 12 grams, or about 0.4 ounces, each...

[wolfe10]

Alan,

You are correct-- sensor weight varies by manufacturer.

From TST's website http://tsttruck.com/faq/:

"Do I need special valve stems?
No, you do not need special valve stems, but you do need commonly available metal valve stems."

"510 wireless sensor weighs 23 grams, and each 507 sensor weighs 13 grams"

"510 sensor batteries last between 5 and 7 years and the 507 batteries are intended to be changed approximately every 10-12 months."

This from the Pressure Pro website:

SPECIFICATIONS
SENSOR
Sensor Transmit Range Approx. 300 feet (Line-of-Sight)
Operating Frequency 433.92 MHz FM
Operating Temperature Range -40°C / -40F to +150°C / 302F
Sensor Weight 2/3 oz. or 17 grams
Sensor Dimensions 1.01" H x 1.11" Dia.

Pressure Pro recommends metal valve stems in their installation guide.

[Walt2137]

Well I have used Pressure pro since right after they marketed the sensors in 04 and have now used TST the last 3 yrs and have never had a problem with the rubber valve stems on a Honda, chevy Equinox , Ford Edge or a F150 and will be using them on the Chevy Spark. You will know if there is a problem with the stems leaking if the sensor is installed.

[whiteeagle]

I've use Pressure Pro on Jeep towed rubber stems for 5 years without an issue.....

[wolfe10]

Because metal stems are recommended by both TST and Pressure Pro (see my post above from their websites), let me suggest that we may have posts reflecting "best practices" vs "what I got away with". Certainly up to you which approach you take.

[tireman9]

As with almost everything technical about tires there is no simple answer. Not all "rubber valves" are the same. and not all TPM sensors have aluminum stems. The problem is how to know what you have.

Basic "rubber stems" such as TR413 as seen at this web page (Note the price) are rated for 60 psi max. There are short and long versions of this stem that except for short brass threads at the end are all rubber. I would NEVER use an external sensor on this type of stem and expecially not on the longer TR 418

Many OE TPMS have aluminum stems and an aluminum nut on the outside and may look like this

Some newer OE TPM sensors have what looks like a standard TR413 but actually have a brass core like this.

You can read about bolt in high pressure stems HERE.

Now I personally have aluminum stem internal sensors. I also use external sensors when doing comparison testing of different TPM systems. I would also use external sensors if I had the OE brass stem sensor or just a standard metal bolt in stem.

Without some more information it is impossible to know what you have on your vehicle. Sometimes just looking at external aluminum is enough sometimes more investigation is needed.

IMPORTANT INFO. You cannot simply look, see rubber and assume that you have a TR413 type stem. The fact that you have not failed a stem does not mean you provide testimony that it is OK to use external sensor on any stem that appears to be rubber.

Based on this thread I will try and write a full post or article on this topic soon.