TPMS question

It senses the pressure in the tire.

 

it's an actual sensor located in the valve stem of the wheels.. they've been like that since 2008.. and they measure the pressure inside the wheels themselves.

 

I just inflated my tires to 40/38 and reset the TPMS. Do you know what pressure drop (pounds or percentage) will trigger the low pressure warning?

 

at the top of my head.. no... i'm not sure it's about pressure drop as in the actual pressure itself that it reads. i'll look it up and report back.

but the one thing i've noticed in other cars is yea.. the sensors work pretty well.. it'll display the light if one of the wheel's pressures are low.. but i've only seen like.. really low.. so i'm unsure of the threshold.

also.. some other cars have one in the spare tire as well and if the spare is low, the light also turns on.. sorta an annoyance sometimes.. but afaik, we don't have one in our spare.

 

They may work both ways, with a minimum pressure and a pressure differential.

 

My wife's Mazda5 has them, and her low pressure light came on a few weeks ago. I didn't have an accurate gauge at the time but none of the tires was visibly low. Of course the low one was the last of the four I checked; it's been OK since.

 

It's normally requires about a 25% drop to trigger a TPMS warning. I assume the Prius c is similar, but I have no hard evidence.

Tom

 

Another TPMS question:

I'm getting some snow tires mounted on steel wheels bought from Discount Tire. Discount Tire says that I need to either swap out my current TPMS sensors ($40) and purchase a TPMS Rebuild Kit ($30) or get a whole new set of TPMS sensors (about $300) put onto my winter tires. I’d rather go the winter w/o TPMS instead of paying for the swap and kit or a new system, but they said they can’t put a non-TPMS wheel onto a car that has TPMS due to a government regulation. Too bad.

However, if I don’t want to buy a whole new set of TPMS sensors, do I really need the $30 rebuild kit if my current wheels/tires will have only about 7000 miles on them? I was told that I’d have to pay for the sensor swap and rebuild kit ($70 total) every time I swap my tires. Including this initial swap/rebuild, I could almost buy a whole new set of sensors for the price of just two winter’s worth of swaps. Does anyone know how often the TPMS rebuild kit needs to be replaced?

Thanks.

 

I just came from discount tire I ordered a set of blizzaks ws70 175/65/15(PM costco $384 including install) . I also purchased 4 TPMS buy 3 get 1 for $75 each. $225 total. I ended up paying $627 including tax OTD. I like this set up because I don't have to swap the tmps every time I change to winter/summer tires.

 

You can purchase winter tires mounted on wheels without TPMS sensors. I have done it for several years with no hassle from either local stores or from Tirerack. TPMS is a big waste of money and buying a second set of sensors is wasting even more money.

 

The tire shop can't tamper with or disable the TPMS on the car, but they can sell wheels without TPMS. Here is what the NHTSA says about it:

At first blush this sounds like a prohibition against selling wheels without TPMS sensors, but what it really says is the dealer or tire shop cannot disable the system. Without sensors the TPMS will display a warning light, which means it still works and is legal.

Full link:
Tire Review - The Final Word: NHTSA Clears the Air on TPMS Regs and Plus-...

Tom

 

I called discountire today and cancelled the tpms that I ordered. I told them to just mount and balance the tires when they arrive to my separate rims and I will install it myself.

 

Thanks for the info and link.

Did the tire shops you dealt with put the wheels w/o TPMS onto your vehicles, or will I need to do this myself if I go this route?

 

I run winter tires the entire year, so I don't switch rims, but I do know of tire shops that have no problems mounting rims without TPMS.

Tom

 

I have a new 2013 c4 .. I don't think i have tpms on my car.. is it on the c ?...

 

All cars nowadays have to have some sort of tire pressure monitoring system, it's the law.

 

I checked the manual and looked for it on my display panel.. nothing?

 

Yes, your C has TPMS. Cycle the power on and watch the dash warning lamps and you'll see the
TPMS lamp as it goes through a bulb test.