Well, here goes my first big thread on this forum. I have spent countless weeks searching for answers to questions regarding TPMS and new rims. I bought a new 2008 FJ in Sandstone last October. In the deal I negotiated with the dealer, I had him substantially discount a 5 rim set of TRD rims for it. I didn't want the extra package because at $1899 I figured it would be cheaper to just get the rims and wheels myself and in the meantime keep the factory rims as a nice set for winter or longer trips.
Anyway, nowhere have I been able to find a definitive answer on anything regarding turning off TMPS on the FJ or what the law actually calls for - in regards to my new rims. So based on some threads here I decided to just live with the light and get some BF Goodrich All Terrain tires for the TRD rims and just put in some "normal" valve stems. I got a good deal at Costco for the tires, however they refused to put them actually on the vehicle without having a TPMS sensor for each of the new tires. I figured that was a total bunch of bunk, but they refused. So I had them mount the tires and not put them on the FJ and I said I would put them on myself. They were sorry the whole thing, but they said it was the law that wouldn't allow them to actually put them on the vehicle. I did get the tires on the rims... just not actually placed on the vehicle.
Which brings me to this post and what the ACTUAL requirements of this law are and what poor analysis was done on behalf of our gov't. Now I'm no lawyer, but this is just my observation on what I've been reading.
You can find information regarding the TPMS law here:
Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays
NPRM on TIRE PRESSURE MONITORING SYSTEM FMVSS No. 138
WHAT TRIGGERS TPMS in my FJ?
First, it appears that the monitoring system in the FJ (as per my observation as well) only lights up when any tire falls below a 25% value of the correct tire pressure for the tire. In other words, if your TPMS system is calibrated for 40psi per tire, it will only light up when any tire is under 30psi. There is no comparison between tires with this system. So, if you are looking for new rims or new tires that have a different PSI requirement, be aware that if the new requirement strays from the delivered value on your current TPMS, you may have to go to the dealer to have them recalibrated - which I understand they can do.
Here's an excerpt from the above link(s):
"Overall, we tentatively conclude that the 25 percent threshold adequately captures the circumstances at which low tire pressure becomes a safety issue. We also believe that this level would be acceptable to most drivers and would not be considered a nuisance to the point that it would be ignored by large numbers of drivers. We also believe there is no reason to examine higher thresholds (e.g., a 30 percent threshold), since they would provide fewer benefits for similar costs."
CAN I DISABLE TPMS?
The short answer appears no - at least not by any concoction of turn ignition on, push this button, blah blah blah. I would guess you would have to somehow disable the system by your own means - physically. In this case, from what I've read you may be causing yourself issues later down the line if you want to sell the vehicle or need to pass an inspection. Some states, I read, now require that for your 2008 and beyond vehicle to pass inspection that you must also pass a TPMS test. If you don't and fail and you will have to pay to get it up to inspection standards. Just an FYI depending on the state you live in.
According to the NHTSA:
"We continue to believe as a general matter that it would be inappropriate to permit any manual or automatic disablement of the TPMS. However, should the unusual events cited above occur, manufacturers would be required to alert the driver regarding impairment of the TPMS through a system malfunction warning."
What I conclude from this: there is no way Toyota will ever be able to offer an option to manually override the TPMS like you can for say, a passenger airbag.
WHAT DOES THE GOV'T THINK THE COST IS?
In reading the TMPS standards, it appears that the gov't estimates that the total cost to implement a system on a NEW vehicle is around the following (this is on the NHTSA site, but here are the figures):
"The costs of the Beru direct measurement system are broken into the following categories (1 control unit at $44, 4 wheels electronic modules to measure tire pressure and transmit the data at $32, 4 reception antenna at $11, 4 valves at $7, the instrument panel display at $2, assembly and miscellaneous costs at $10) for a total of $106.
The costs of the SmarTire direct measurement system are broken into the following categories (1 control unit which includes one antenna at $30, 4 wheels electronic modules to measure tire pressure and transmit the data at $30, 4 valves at $5, the instrument panel display at $4, assembly and miscellaneous costs at $11) for a total of $80.
The costs of the Johnson Controls direct measurement system are broken into the following categories (1 control unit which includes one antenna at $19, electronic sensor modules in the 4 wheels to measure tire pressure and transmit the data at $30, 4 valves at $7, the instrument panel display at $4, assembly and miscellaneous costs at $9) for a total of $69.
...
Based on the three direct measurement systems costed out in the teardown studies, the average price for the tire pressure sensors is about $7.50 per wheel or $30 per vehicle. "
NO WHERE have I seen that it would be that cheap to put additional sensors on my tires. I looked around and the cheapest I could find was about $90+ dollars at an online dealer - for EACH sensor. For 5 tires that brings it up to $450 just in sensors - no where near the $30 in the gov't report.
Factor in also that the TPMS sensors only last 5-7 years based on their battery life - and I understand that battery replacement is not an option - you must get new sensors. So, in this case, I am a little bit ticked that it is costing so much. If it WERE $30 for my vehicle to get them, you can bet I would have.
OTHER THOUGHTS.
Now, I'm not going to say that the data on the NHTSA website is wrong with the facts regarding fuel savings and potential injuries/lives saved per year and what not. I read all the facts. I'm not saying there isn't a benefit. However, the cost they site for this benefit is WAY off compared to what we are seeing in the real world. I just wish this option was not so costly - after the purchase of the vehicle.
Additionally, I've read on some threads that Toyota will store up to two sets of tires/rims in the system? Can anyone confirm this? I would think it would need to hold two sets of tires/rims with 5 tires being in each set for a total of 10 TPMS sensors. 4 per set is just not going to cut it.
Anyway, those are some extra thoughts on this topic and some sources for you to read up on if you are interested. If you have any other thoughts please post.
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