I gathered from my experience that some speed or distance is
necessary. I wonder at the devices, do they need the rotation to
generate the power to send a signal? Yet the web page for the
manufacturer suggests they have a device that queries them at rest. I
still don't know how they get the signal to the dashboard, some form
of RF I guess, bluetooth or some other frequency.
Yes, I do.
Good idea. I knew I should have put another pound or two in, to
guestimate the right numbers "warm".
Ha. Takes a fair amount of pumping a hand-pump to move a car tire
1psi, and the connections often leak just about that fast.
Sure, but I assumed that three tires were good and one was lighting a
sensor, and you'd think that might be visible. In my case they were
all just about equally low so there was no real visible difference.
I don't grok this, why would rotational difference set off a pressure
sensor, do these things cross-check each other? I can't figure why
that would help.
So, do the dealers have a lot of customers with these kinds of issues?
When I next bring this car in for service, I'm going to mention the
low pressure to the service manager and the front office. The only
way the four wheels had the same low pressure, is if that's how they
gave it to me. I do recall in the past, some guy at the dealership
said they ran them low because "it gave a smoother ride". Guess he's
still working there. Can't be good for the tires.
There are two kinds of TPMS. One is ABS-based (rubber valve stem), and
the other is transponder-based (steel valve stem).
Transponders are incorporated into the valve stem. They work a bit like
cell phones, in that they have batteries and emit a radio signal. That
signal is received by the TPMS computer. Eventually, transponder
batteries will go dead and need replacing. Draw on the batteries is
tiny, so it will be years before they go dead. But when they do, imagine
all those irate customers! Thank you, Congress.
ABS-based requires actual tire rotation to determine if one tire is low.
Transponder-based does not require tire rotation. As I understand it,
transponder-based systems wait a bit before deciding that there's a
problem, even though they /could/ snitch immediately if they wanted to.
I'm not sure why.
My Schwinn pump does about six pumps to the pound. I consider it
There is no appreciable leakage from the valve stem when the pump is
connected to it.
Nope. No obvious visual difference until they're about 15psi low.
Rotational difference is used on ABS-based systems. ABS-based systems do
not have sensors inside of each tire. Measuring and comparing rotations
is the only way they have of being able to tell if a tire is low.
Transponder-based systems measure tire pressure directly, using sensors
inside of each tire (and sometimes even inside the spare).
Yes. Just like EVAP.
If he said that, then he's a dummy.
Probably not. But this monkey is not too smart if he thinks he's smarter
than the Honda engineers that designed your car. I'd trust the Honda
guys before I trusted some goofball working for a dealership.
Must disagree. I can't tell pressure on some arbitrary tire on an
arbitrary car, but I can get used to what my own tires look like
properly inflated, and notice a different curve as they get low. I've
had to deal with leaky tires before and had practice.
OK, I see. Sort of. Funky.
I think the logic is that Honda has to overinflate them to get the EPA
mileage up, but that for a mile a gallon or two, you can get a better
ride with lower inflation.
Might even be somewhat true, but even so, they overdid it.
Yup, EVERY manual says to never bleed air from a hot tire.
I've autocrossed with a lot of people who use bleed valve guages. If
you're up for the ~$400 price tag.
That's the point. Not that they were "equally" low but that one may
have been "too" low and the others were "just above" the limit.
But I always check mine. For exactly the two reasons you and I
The sensor is actually ABS based (as opposed to the F1 sensors that
really are pressure based). ABS measures the rotational speed to
figure out which tire is locking up. Unless your tires, rotars, pads,
pistons and master are all incredibly tuned up, one tire will lock
first. Stay up late tonight (if you're in the western hemisphere) and
watch one of the bought drivers in the GP of China square off a tire.
That is pure BS. Doing that introduces a huge number of safety and
A lot of drivers I AX with (including me) will sometimes chalk the
tires looking for roll. Too low a pressure and too tight/fast a turn
will roll a tire off the rim. I've seen it.
Never AX'ed, myself, but I'd wager that you just put a chalk line down the
sidewall and onto the tread. Where the line gets scrubbed away, the tire's
touching the pavement.
The idea would be to maximize the amount of tread remaining in contact with
the road instead of getting lifted off as the sidewall rolls under.
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