Tire Pressure Sensor in Spare?

[qbee42]

Originally Posted by jay_man2

The bad thing about the spare is that the the way it's stowed the valve stem is face down, so it's a major PITA to pull the cargo box out, pull the spare out, then check the pressure.

If you flip the car upside down it's much easier to get to the valve stem and check the pressure.

Tom

[stream]

Originally Posted by jay_man2

I used to check tire pressures every Saturday morning, along with the fluid levels and battery indicator (the green or blue eye on a 12v battery). With the advent of TPMS, I'd completely fallen out of that very useful habit, but I'm trying to work it back into my weekend routine.

I check my tires monthly--give it a try--weekly is probably a bit overkill, and the monthly schedule is more likely to be performed. The TPMS threshold is so high (8 PSI as I recall) that I wouldn't want to rely on it, short of when you get a flat tire.

[stream]

Originally Posted by jay_man2

The bad thing about the spare is that the the way it's stowed the valve stem is face down, so it's a major PITA to pull the cargo box out, pull the spare out, then check the pressure.

You could attach an extension hose to the valve stem:
Chek-a-spare, Check-a-spare, tire gauge guard

They make excellent quality pressure gauges--here's the one I use:
Dial Tire gauges

[tumbleweed]

The spare holds air pretty well, I usually check mine once a year and put 65 or 70 lbs in it. If I need to use it I'll check it and let a little out if needed.

My cynical side says the reason the TPMS sensor ID can't be changed by the car owner or even the tire shop is because dealers have pressured manufacturers to have a lot of simple stuff on the car that only they have the software to change. That way the dealers can charge an hours expensive labor to shut off the annoying backup beeper or change the sensors, which should take no more than 5 min.

Unfortunately it works because to many customers think "Toyota knows best" or "if the dealer said so it must be true".

OK, now I'll climb down off my soap box.

[Boo]

AFAIK, a tire pressure sensor in the donut spare wouldn't work because the 4 regular tires have a recommended psi of around 35 psi, while the donut spare has a recommended psi of around 60 psi(?).

So if the Tire Pressure Monitoring System were set for the 4 regular tires' 35 psi, and the donut spare had a sensor in it, the donut spare would have to be at around half of its recommended 60 psi in order to trigger the TPMS warning light.

Although this would be somewhat useful, I'd rather save the $100+ cost of a tire pressure sensor in the donut spare.

[jayman]

There are some vehicles that allow you to register two sets of TPMS id's, but AFAIK these are luxury import SUV's. The principle behind the luxury import SUV allowing two sets of TPMS keys is that one set can be used for the normal tires/wheels, the second set for either off-road or studded winter tires on separate wheels

[qbee42]

Originally Posted by jayman

There are some vehicles that allow you to register two sets of TPMS id's, but AFAIK these are luxury import SUV's. The principle behind the luxury import SUV allowing two sets of TPMS keys is that one set can be used for the normal tires/wheels, the second set for either off-road or studded winter tires on separate wheels

Kind of odd too, when you consider that the additional cost in electronics is next to nothing. The logic and memory requirements are trivial.

Tom

[Boo]

Probably in the future, TPMS will have at least 4 settings -- one for each tire -- and show exactly which tire is underinflated.

[stream]

Originally Posted by Boo

Probably in the future, TPMS will have at least 4 settings -- one for each tire -- and show exactly which tire is underinflated.

Some TPMS systems show the actual tire pressure for each tire.

[Boo]

Originally Posted by stream

Some TPMS systems show the actual tire pressure for each tire.

That would be ideal. Which car has that now?