Any interference with dual TPMS systems?

[kannonvaggon]

I've decided to install a TPMS system on my tag-axle coach. I've been " assured " by both TST and Darlan/ pressure-pro that if I install one of these 12 tire systems there will be no problemo with the coach xpndrs blanking out the car xpndrs or vice versa, etc....

In our case we'd be putting a valve stem sender right on top of the in-tire sender of the Smart. It appears that the two units would be at discrete frequencies and also have somewhat different encoding... but I wondered about RF type of interference? Just wondering....

I'm gonna spend the money on the TPMS for the coach for a couple reasons. MOSTLY it's so I won't have to go out and check all them tires, usually in the rain of course, every morning when on an extended road trip. The display will tell me every tire's pressure and temperature. This would be pretty handy.
Secondly I don't think I would be able to tell if the Smart-toad had a low tire until the point that it tore up the tire or maybe a wheel..... I'd rather know about a flat tire relatively early in the process?
Lastly, I would like to be able to monitor the effect of steering axle loading as regards tire temperature rise. My coach is somewhat heavy on the steering axle and on real hot days it would be nice to be able to see what's goin on down there, and if in fact I'm running more PSI than I realy need to, etc...

Any body running dual senders on yer Smart? Any problems? Do the senders make the little bugger jump up and down like a Mexican jumping bean?? ;-)

I know I can mitigate some of the antenna effect of the coach senders by going with a Smart-tire or other system with senders inside the wheels, but this is rather expensive up front and ongoing.... and also isn't portable at all... and ya have to run two repeaters on my type of coach apparently due to attenuation. I may or may not end up with a rear repeater for the SMart-toad back there in any case... I'm thinkin it will probably work fine without it but ya never know until ya try it I guess. I'm lookin closely at the TST system right now. Maybe Santa will come through with some cash, ya never know....

[fortow]

I use the Pressure Pro system on my motorhome but don't bother to install senders on the smart.

I use it for the same reasons you outlined - to know what the cold pressures are, to know how much the pressures increase under varying conditions, to be able to tell if there is a leakage problem. I found that pressures can increase between 10-15 lbs depending on weather and speed. I also found that some tires increase in pressure more than others. My cold pressures are 110. Over the season they lost about 10 lbs.

If the power is not on in the smart then there should be no interference. It wouldn't be a problem anyway if the transmitter frequencies differ. When driving the smart, if you leave the external sensors on the smart valves they won't be sending if they don't receive a signal from the in-coach display unit anyway.

You may have a concern about tire balance with the smart though. get the tires re-balanced with the external sensors installed.

Have you contacted Pressure Pro with the same questions?

[kannonvaggon]

Yes. Pressure Pro seems to be the pretty much the same as the Dolan if I recall correctly?

Everybody pretty much is sayin that there wouldn't be any problems with having the dual senders on the Smart. They are also sayin I will need a rear repeater.... but I still think I'll get a system and install it and if I then have issues picking up signal from the Smart THEN I'll have em ship me a repeater.

I haven't made up my mind on which system to get yet. I like the Smartire system but I just can't see having to take off all the tires and put in the senders and then have to balance the tires again and install two repeaters under the coach. If I trade coaches then I have to probably just leave the system and get a new one. The senders on the Smart would be a PROBLEM. So, that leaves out Smartire.... Nice unit though... ANY of these senders added to the Smart would probably require a re-balance of them teeny tiny tires ....

The TST and the Pressure Pro are very similar. They use slightly different sender units with different locking mechanisms apparently. I've read of several folks that have had PP senders depart the coach and or get a leak. I've only read of ONE TST that got a leaky sender. I think there are more PP units in coaches and more TST units on commercial trucks, but I could be way off on that. That might account for not having as many posts on the boards concerning losing a sender. More PP units means more probability of a fault... ?

Both of em seem to have good range and battery life and a good warranty.
From what I can tell with either system I will need to install angled valve extensions on some of the wheels of the coach and MAYBE on the Smart. I guess this is to gain some clearance so the senders don't touch the wheels and to turn one pair around 90 degrees so they aren't facing inboard toward the hub.... Apparently this is normal.

The current "deal" on the TST is a 12 sender system including a long antenna AND a repeater for under 400 bucks including shipping with a 2 year warranty and they will swap senders when the batteries go low for 25 bucks. That isn't a bad deal from what I can tell. I didn't see a price close to that for the PP system. I might be missing something. It wouldn't be the first time.

I'm thinkin it's a bit more of a PITA to add air to your tires, but on the other hand yer not out checking tires all the time and HAVING to add air just because you are checking them all the time... I'm like you in that the tires actually don't lose hardly any air pressure in a LONG time. Temperature compensation is a feature on the new TPMS units that seems like a good improvement.

My understanding of the senders is that they DO send a message whenever they sense any PSI, every 5-6 minutes... and immediately when there is a fast leak or high temperature alarm condition. They only stop using battery power if they are removed so they do not sense any pressure. They will transmit whether or not the display head receives it ....
I might be mistaken yet again...

Santa WANTS a TPMS system..... He desires it .....

[fortow]

Originally Posted by kannonvaggon

...
My understanding of the senders is that they DO send a message whenever they sense any PSI, every 5-6 minutes... and immediately when there is a fast leak or high temperature alarm condition. They only stop using battery power if they are removed so they do not sense any pressure. They will transmit whether or not the display head receives it ....
I might be mistaken yet again...

You might be right, and that may be why they recommend not leaving them on the wheels if the coach is not being used.

What is the situation with any TPM sensors? They all must be active and using their battery power when they are installed then. I guess they haven't been available long enough to know what the average life expectency is.

[kannonvaggon]

I THINK the life of the batteries is about 5 years. They say it's 5 to 7 years. Some senders have batteries you can change yourself and some need to be done at the factory so they pretty much just exchange them. They usually have a low battery indication that gets sent to the display when they get close to being done.

I haven't read up on what the deal is on the TPMS senders in the Smart. I might have to check that and see if one can change the batteries or not. Nobody has one old enough to get low batteries yet assuming they hold up for over 5 years I guess...
One would want to do this when changing tires supposedly, cuz I'm thinkin yer gonna have to pull the tire off the rim to get to the unit...