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Old 10-16-2012, 10:02 AM   #29
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FWIW from what I can ascertain, the Hawkshead system is made by Tire Traker which is the one in my link. This one is the latest design w/ the new monitor design. My only concern w/ the flow-thru sensors is the extra weight hanging on the valve stem.

As to the tire temp. discussion, couldn't one simply add air to the tire and see if the temp. reading increases? If it does, then it's calculating temp. from pressure. If it doesn't then it is doing it some other way.
Maybe....depending on the "turn on/turn off" logic, if a particular system has it. It would be an interesting experiment. I'd bet you would have to have the pass through fill though. I think most of these sensors shut off when removed. That may set a new baseline at ambient vs. new pressure setting in tire when reinstalling the sensor.
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Old 10-16-2012, 11:49 AM   #30
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I believe we should all be aware that unless the sensor is inside the tire, it cannot read temperature. I believe these systems use a formula to calculate pressure rise and ambient temp, and then calculate an internal temp by using the1 PSI= 10*F rise in temp.

If you use your noodle, all of them tell you the temp, if you can do a little math.
I do not believe that your calculation theory is correct for Hawks Head or tire minder at least. If someone really wanted to know for sure they could verify with the manufacturer.

This is what I was told by Hawks head. The temperature sensor reads the temperature of the air in the valve stem. I will readily admit that especially while in motion, this is probably somewhat less the the temp in the center of the tire.

Regarding metal valve stems:
I had this discussion about them when I first got the TPMS. I asked Discount tire to install metal stems on my wheels. The manager asked why, and when I told him, he said that the stems on my tires were already metal covered by rubber and should work fine. I called HawksHead and asked him about this. He said yes this is correct, and told me he includes the metal stems with the units because they are inexpensive, and so many RVers were adamant about wanting them, and he was tired of trying to convince them they were not necessary. As I think about it now, it seems that rubber covered is better because it insulates the valve stem.

Personally, I am not interested that much in absolutes as I am in changes as I drive. I am not saying that is correct. I am only saying that is how I feel about it.

Ken
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Old 10-16-2012, 01:06 PM   #31
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Bought my system at the Tire Rack.com.Inexpensive and works as it should.Gives pressure and individual tire temps with alarm.Comes with metal valve stems and the sensors are inside the tires.They go into sleep mode when trailer is not moving and wake at 20mph.I monitor 4 tires continuously.I would not travel without it.Dill is the mfg.Price $239 complete
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Old 10-16-2012, 01:13 PM   #32
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the sensors are inside the tires.
Excuse this probably dumb question. Do the tires have to be removed from the rims to install and/or service the sensor?


Ken
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Old 10-16-2012, 03:45 PM   #33
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Bought my system at the Tire Rack.com.Inexpensive and works as it should.Gives pressure and individual tire temps with alarm.Comes with metal valve stems and the sensors are inside the tires.They go into sleep mode when trailer is not moving and wake at 20mph.I monitor 4 tires continuously.I would not travel without it.Dill is the mfg.Price $239 complete
These are the most accurate for temps, but are still a ways from the hot part of the tire.

These are just like OEM sensors, except with a temp feature that FMVSS does not require of automakers.
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Old 10-16-2012, 03:50 PM   #34
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I do not believe that your calculation theory is correct for Hawks Head or tire minder at least. If someone really wanted to know for sure they could verify with the manufacturer.

This is what I was told by Hawks head. The temperature sensor reads the temperature of the air in the valve stem. I will readily admit that especially while in motion, this is probably somewhat less the the temp in the center of the tire.

Regarding metal valve stems:
I had this discussion about them when I first got the TPMS. I asked Discount tire to install metal stems on my wheels. The manager asked why, and when I told him, he said that the stems on my tires were already metal covered by rubber and should work fine. I called HawksHead and asked him about this. He said yes this is correct, and told me he includes the metal stems with the units because they are inexpensive, and so many RVers were adamant about wanting them, and he was tired of trying to convince them they were not necessary. As I think about it now, it seems that rubber covered is better because it insulates the valve stem.

Personally, I am not interested that much in absolutes as I am in changes as I drive. I am not saying that is correct. I am only saying that is how I feel about it.

Ken
Well....I disagree, but that's the way it is. I think stem temp is WAAAAAY too far away from what matters to be of any value...without some sort of mathematical correction.

I am truly plagued with a need for absolutes....right or wrong, that's the way I'm built. That's why politics drives me bonkers!!!!

I am sure each brand does it differently anyway, so until then, I'll use my mental pressure to temp math. Now, if I could find any credible source to tell me how hot is too hot for tires, it would definitively let me determine what pressures to run in the tires.
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Old 10-16-2012, 03:51 PM   #35
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Excuse this probably dumb question. Do the tires have to be removed from the rims to install and/or service the sensor?


Ken
Yes, a dismount and remount/balance is required.
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Old 10-16-2012, 05:04 PM   #36
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Well....I disagree, but that's the way it is. I think stem temp is WAAAAAY too far away from what matters to be of any value...without some sort of mathematical correction.

I am truly plagued with a need for absolutes....right or wrong, that's the way I'm built. That's why politics drives me bonkers!!!!

I am sure each brand does it differently anyway, so until then, I'll use my mental pressure to temp math. Now, if I could find any credible source to tell me how hot is too hot for tires, it would definitively let me determine what pressures to run in the tires.
If you think about it you can't disagree, you can only feel differently. That sounds much better. I was simply talking about how I feel about it, not what I think is right or wrong. I'm going to keep that secret.

For me, the purpose of the TPMS is to make me feel better(more relaxed). If I start analyzing it too closely I will start to worry about whether it is doing it the best way possible. Then it won't be serving its purpose. I prefer to just assume it is doing its best, and feel good that is there.

Ken
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Old 10-16-2012, 06:02 PM   #37
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If you think about it you can't disagree, you can only feel differently. That sounds much better. I was simply talking about how I feel about it, not what I think is right or wrong. I'm going to keep that secret.

For me, the purpose of the TPMS is to make me feel better(more relaxed). If I start analyzing it too closely I will start to worry about whether it is doing it the best way possible. Then it won't be serving its purpose. I prefer to just assume it is doing its best, and feel good that is there.

Ken
True, and well said. But, after living the ramifications of the Ford/Firestone issue (which resulted in TPMS being required on all light duty vehicles) I am particularly sensitive to this issue. There was MUCH that was never made public about that whole thing that is SCARY!!!! Simply feeling comfortable as a panacea is not good enough for me. I NEED to know more. "Trust but verify"
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Old 10-17-2012, 12:19 AM   #38
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Yes, a dismount and remount/balance is required.
Not necessarily. The dealer is going to replace the OEM TPMS units on my wife's Tahoe and all they do is break the bead next to sensor and R&R and reseat the tire.

I asked one of the vendors how they measured the temp.
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Old 10-17-2012, 07:05 AM   #39
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I have this item for sale in the classified. Orange Electronic P409S Retrofit Tire Pressure Monitoring System I was going to use it on a trailer but sold the trailer instead.
It highly rated and new in the box. $120.
It's highly rated, but not for trailers... or crew cab even trucks for that matter. People are complaining that it won't read the rear right tire on an extended cab pickup. Do you have some sort of repeater for it to make it work? Otherwise, there's no way that'll work for the trailer with the brains sitting in the truck.

Furthermore, the highest alarm setting is at 60psi. If you fill your trailer tires to 65psi as recommended, you'll have to turn off the alarm every time you start your vehicle, and keep a close eye on the monitor as there'll be no usable alarms.
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Old 10-17-2012, 08:01 AM   #40
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Not necessarily. The dealer is going to replace the OEM TPMS units on my wife's Tahoe and all they do is break the bead next to sensor and R&R and reseat the tire.

I asked one of the vendors how they measured the temp.
Ah, that's true, didn't think of that shortcut.

What did the vendor say?
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Old 10-17-2012, 07:05 PM   #41
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Just a follow up.
After 2500 miles with my TPMS (a DILL), it's one of the most useful additions I have made to my rig. It is fantastic to be able to check all my pressures while hitching up, and then monitor them on the fly. I've been in every kind of temp and elevation and road, and it's great to not be worried about a tire you can't see or feel. For all who can afford to add this, you will find it a good investment I think.

Tires is kind of the "biggie" while towing, and the more you know about what they are doing, the more confident you can feel. Now, if only there was a similar device to read out the lug nut torque....
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Old 10-17-2012, 08:25 PM   #42
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Ah, that's true, didn't think of that shortcut.

What did the vendor say?

They both said that it measure the air temp. at the valve stem. From that statement I concluded that it's an actual temp. measurement, not a calculated value from pressure change.

One was Tire Traker and the other was TST from Great RV Products.

I'm pretty sure that to put them on the rear, I'd have to remove the outer dual. Then to add air I would have to do it again. While the TSTs have a flow-thru version so you can add air w/o removing, I think the size would preclude installing on the duals. It's enuf of a PITA to add air now.

I think I've talked myself out of the external mounted TPMS. Maybe when I need to replace the tires, I'll look into some internal mounted ones.
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