Know about TPMS? You will, and soon
We don't need to tell you that under-inflated tires can zing your mpg for a few percentage points, do we? You know that keeping your tires correctly inflated means you're helping to get the most miles per gallon you can, right? Good, cause it's something we should all know by now, and there are only so many ways to write it.
Something that we don't always know is when our tires are under-inflated. Some people check their tires regularly. If you're one of them, you can stop reading now. For the rest of you, if you'll take a moment to familiarize yourself with the orangish shape above, you soon will be able to tell when your tires are plumping out, as all new cars, starting with 2008 models, will have TPMS, a tire pressure monitoring system. When you need air in the tires, the symbol above will appear in the dashboard, telling you it's time to visit a pump (BTW, is there a site that tells you which gas stations still offer Free Air pumps? Because there totally should be).
The Auto Alliance is promoting TPMS as a new safety feature, but it's obviously more than that. Following a long spiel about how flat-ish tires can be dangerous to drive on, the Alliance's press release announcing the standard TPMS systems says that fuel efficiency is reduced one percent for every three-PSI under-inflation. Don't make me repeat that.
[Source: Alliance of Automobile Manufacturers]
Reader Comments (Page 1 of 1)
chas 9:56PM (3/17/2008)
You want real tpms info here it is. First air pressure should be set by the vehicle calls for. Example most cars call for about 30psi but the tires call for 44psi what the vehicle recommends is right. For trucks it is more important like f250
most say 60f-80r make sure the tires can handle up to 80 psi crucial for towing and and safety. If read the side of a tire and the max for air is 65psi your tires are not strong enough. Just some tips for air pressure. For tpms it is here to stay.
everything 09 and newer must have tpms. A word to dealers who want to continue to serve customers learn about tpms it is here deal with is. To the average consumer most are lost and don't have a clue on what the system does other then seeing a light on the dash and thinking your tire is flat.
The sales people seem clueless as well. all they say it is is a new govenment mandatory thing at least that what I learned from a customer with brand new Grand Caravan. Here other info that a consumer should know that isn't learned until things go bad and need a tire replaced. DON'T USE FIX A FLAT OR ANY TIRE SEALANT IT WILL EAT THE SENSOR. That 3 dollar can will cost between 30-120 for a new sensor.
The shiny chrome and/or colorful valve caps usually aftermarket are bad also. Why you ask.
they fit fine but the caps seem to oxidize or seize up on the valve and when that happens the caps don't usually come off. How about a pair of pliers. DON'T DO IT ! YOU WILL BREAK THE VALVE. Then you will need to replace the sensor. What should I use for tpms. what came on the vehicle either the typical gray caps. Some are tin. Some are black. Tpms is supposed to work for us if used properly. You should check airpressure your once a month. The tpms also warns you when a tire is low. but what if 3 tires are at 45psi and 1 tire is at 35psi? What if a vehicle says the tires should be at 30 psi but the light comes on what do you do?
Do you go to a tire place and say all 4 tires have flats just because the light goes on.
Or go through the process of elimination.
get a good air gauge. then check the air.
here is a few scenarios. say you use an air gauge and have 3 tires at 30psi and 1 tire is at 15 psi the low tire needs repaired. how about this a car is supposed to have 30 psi but the light comes on. but you check the air pressure on all 4tires and it reads 25psi. only 5psi is lost. so then add the 5 psi that is lost. it should clear the light on the dash. if you see the light again say in a few days then go through the process of elimination to see if a tire is bad. here are some tips when you are checking air at the 50 cent air station.
Have your own air gauge the ones at the air stations usually don't work or are inaccurate.
remove all the air caps maybe put them in your pocket so you don't lose them.
Check the air in your tires first before any coins go in the air station maybe it is only one tire that needs air.
Make sure the air hose can reach to all 4 tires BEFORE you add the coins.
Air is still cheaper then gasoline.
Good luck drivers
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Stevo 12:41PM (8/23/2008)
I consider myself mechanically savy, yet this tpms light is the true rebirth of the idiot light. If the sensor is inside the tire, it is inaccessible by the owner. $$$. If the driver cannot calibrate the senor for each wheel through the car's onboard computer, it's just another check engine light demanding owners to get soaked by their mechanics. $$$ Come on America. Tire pressure is important, however these sensors are costly, and do little but eventually have everyone driving around with little annoying lights on their dash at nightime. SUVs brought it on, so if a system is designed, at least make it serviceable by the owner through the onboard computer.
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steve 2:19PM (1/13/2009)
Well Stevo, if you are sick of paying a technician for diagnosing your problems on your car (or as you call it getting soaked) then maybe you should get off your cheap a** and spend $700 on a tpms scanner so you can diagnose and reset your own tpms system. They are very easy to use and I am sure even someone of your stature could figure out how to use it. While we are on the subject of getting soaked, maybe you should also pick up a Tech One, Snap on or an OTC scanner for between $2000 and $8000 each (depending on the model) and you can also diagnose your own check engine light (although I am positive you wouldn't know the first thing to do with these diagnostic tools). Stop blaming the system and the people who work on them and blame the asshole trial attornies that sued Ford and Firestone for the ford explorer tire blowout lawsuits. Ignorence of knowledge is always the most valuable asset to idoits like you!!!!
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jr23 2:14PM (4/24/2009)
Another brilliant idea foisted on us by congress
now it will cost a minimum of $5.00 and depending on the car @30
just to have a nail puncture repaired and $20 to @50 to have a new set of tires installed owners of new cars won't realy notice ti'll the cars need new ones or the 2 owners it could in the future cost more lives when the cars get into the hands of the later owners who will not have the money to replace the tires and try to run them longer.
a lot of regulators do not look at the whole picture when they come up with new
regulations they could have tried pressure valve caps firts $5 to $15 a car no
extre costs for repair.
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brad karma 3:48PM (4/30/2009)
QUESTION, . what is an average tire running temperature?
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Travis Rassat 6:08PM (8/29/2007)
In my opinion, this is a nice idea, but I have a couple of initial questions about it:
First off, how much additional cost does this add to cars for the initial price? A couple hundred dollars? More? It seems that this is going to increase the price point for affordable new cars.
Who sets the value for what is considered low pressure? I see more and more cars with a sticker in the door that states the recommended tire pressure for the car, which will be considerably different than the max pressure on the tire the car is equipped with. My current car (which does have TPMS) has a sticker recommending 30 psi, while the tires have a 44 psi max. That's obviously a big percentage difference in pressure. Which is right?
Also, when the tires wear out and are replaced, if I get new tires that have a different psi rating, how does that affect the numbers? Does TPMS have the ability to adjust for this or is it an arbitrary number set by the car manufacturer?
These questions come to mind mostly because I just got a new set of tires for one of our cars (which doesn't have TPMS), and when they installed them, the tire pressures were very, very low. I inflate my tires to 2 psi less than the max. I guess it just makes me wonder who's going to decide what tire pressure is too low.
I'm going to go read up on TPMS and how it works now, so maybe I'll answer my own questions...
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Charles Zucker 3:18PM (9/14/2008)
Tire pressure is always set by the information on the car door. The maximum inflation pressure listed on the tire has nothing to do with what pressure you should run your tires at. Obviously in the pressure indicated on the car is higher than the one on the door you have the wrong tire for your car.
CT-Jake 6:27PM (8/29/2007)
We don't need a monitoring system, we need an automatic inflate system. Most folks don't inflate even when they know the tires need it. There are 9 gas stations between my home and work. Only one has a working air station. It costs 50 cents and you have just enough time to do 2 tires. So, it ends up costing a dollar and you are never quite sure what presure you actually have. Plus, who wants to kneel down on dirty pavement just to inflate your tires. Ladies may have even more concerns. The problem is not people don't know their tires are under inflated. The problem is that it's just too much of a hassle to inflate them. Solution: automatic inflation system!
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Chris M 8:58PM (8/29/2007)
My own experience is that it has a noticeable effect, my milage was decreasing, so I checked and I found one tire has a very slow leak. I'm using a portable battery powered inflator with a gauge, it didn't cost much and is easy to use.
To answer Rassats question: The "recommended" tire pressure is based on the weight of the car and is a compromise between ride, handling, and fuel economy. Higher tire pressure improves fuel economy, but makes a harsher ride and can adversly affect handling (less tread in contact with the road).
The "max pressure" on the tire is the limit that it can be safely inflated to - exceed that, and ride will be harsh, handling poor, and the risk of blowout and tire damage dramatically increases.
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Ping Wang 9:03PM (8/29/2007)
I'm pretty much OCD when it comes to checking my tire pressure, and I think TPMS will be a boon for us all.
One side benefit that you don't mention on here is that a TPMS will alert when it senses a flat tire. (We can't always tell when we have a flat tire, because most people don't check all 4 tires before they get into their car.)
Well, when a tire gets low enough pressure(because of a nail) then you will start to hear a rumpling sound. That means you should STOP IMMEDIATELY. If you drive even a few yards while hearing this sound, your tire is RUINED.
So far i've had 2 flats, which cost me $280 in new tires. I cringe even more when I realize that the ruined tires could have had 40k miles each if they hadn't been ruined, and now they are filling up landfill somewhere.
With TPMS, right when the light comes on, i'll know I need to get out of my car and check the tire to see what's up, and possibly avoid paying for a whole new tire!
P.S. I keep my tires properly inflated with a regular bicycle pump. It's convenient, and it's a great workout!
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James H 8:02AM (8/30/2007)
Too much of a hassle to inflate your tires? You're driving a vehicle that weighs at least a ton down the interstate at 65 mph, and you don't want to take responsibility for the air pressure in your tires? It takes all of 2 minutes to check, could save your life and the lives of others, and will help you get better gas mileage. The inconvenience is more than offset by the benefits. Buy a tire gauge, keep it in your car, and use it.
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hokiebird 9:39AM (8/30/2007)
My car has TPMS. I generally check my pressure when I wash it and I have a pressure guage in the trunk. I can obviously live without it, but it is nice if you get a flat tire. Also, with low profile tires it's a little harder to visually tell if a tire is getting low.
A major downside is if you swap wheels you are going to have a dummy light on.
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regguy 1:21PM (8/30/2007)
Travis, you raise good questions:
At the end are the estimated costs and benefits from the NHTSA Final Rule.
The TPMS must trigger the lamp within 20 minutes of a pressure 25% below the mfr. recommended value. This is the regulation, but your car will trigger sooner. Auto manufacturers establish recommended pressures based on durability, comfort, and load carrying ability. The max. pressure on the tire is for the max. load capacity of the tire, but no vehicle is rated to run at max. tire capacity. Trucks may be closer though.
When a tire is replaced is should be of the same size as on the tire label on the front door or B-pillar. Then use the same psi as the auto mfr. recommends. If you change tire sizes the system won't care since the sensor in the rim will still report low pressure based on the original design. The exception is a vehicle with a less costly "wheel speed" comparison TPMS, but as far as I know, none can yet pass the NHTSA 20 minute multiple tire low test, so they are not available.
You can inflate your tires to 2 psi below the max. on the tire for better mileage, but the ride will be harsher and watch out for center tread wear.
If you have TPMS and change rims you need to be sure that you can use the same rim sensor or the lamp will stay lit.
Costs and Benefits from NHTSA [quote]
Thus, the agency estimates that the average incremental cost for all vehicles
to meet the standard’s requirements
would range from $48.44–$69.89 per
vehicle, depending upon the specific
technology chosen for compliance.
Since approximately 17 million vehicles
are produced for sale in the U.S. each
year, the total annual vehicle cost is
expected to range from approximately
$823–$1,188 million per year.
The agency estimates that the net cost
per vehicle [vehicle cost + maintenance
costs + opportunity costs—(fuel savings
+ tread life savings + property damage
and travel delay savings)] would be
$26.63–$100.25, assuming a one-percent
TPMS malfunction rate for replacement
tires. (Maintenance costs would be
variable, depending upon whether the
TPMS has batteries or is batteryless.) As
noted above, the agency estimates the
total annual vehicle cost for the fleet
would be about $823–$1,188 million.
Thus, using the same equation, the
agency estimates the total annual net
cost would be about $453–$1,704
million.
NHTSA estimates that the net cost per
equivalent life saved would be
approximately $2.3–$8.5 million,
depending upon the specific technology
chosen for compliance. Placing 90-
percent confidence bounds around the
cost per equivalent life saved results in
a range of $1.5–$14.5 million.
Net benefits-costs (i.e., benefits,
including fatalities and injuries, valued
in dollars minus costs) were also
calculated per OMB Circular A–4. The
value of a statistical life is uncertain,
and a wide range of values has been
established in the literature. (In general,
the statistical value of a life is valued in
the range of $1 million to $10 million
per life, with a midpoint of $5.5
million.) For this analysis, we have
examined values of $3.5 million and
$5.5 million, both of which fall within
the range of accepted values. The mean
value for net benefits-costs ranges of the
TPMS standard from a net cost of $597
million to a net benefit of $655 million,
depending upon the specific technology
chosen for compliance. A 90-percent
confidence bound around the net
benefits-costs results in a range from a
net cost of $1,156 million to a net
benefit of $1,302 million.
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