How do you run high tire psi without tripping TPS sensor?

[DaveinOlyWA]

As the subject says, I noticed that when my tire pressure approaches 44 psi (max the tire is rated for), the TPS sensor goes off. I know the TPS is useful to warn against low tire pressure, but how are people running +45 psi in their tires without the constant nag of the TPS sensor warning? Just removing the TPS sensor all-together? I usually run my tires around 38 psi to avoid this (as when it gets hot during the day, the tires seem to gain another 4 or 5 psi from the heat).

Just curious to what others experience here when running high psi to help with hyper-miling. :mrgreen:

your sensors are defective. get them replaced. I ALWAYS run at the max listing on the sidewall in every car I drive. During Summer that usually means pressures hitting 48 -49 PSI. I have never had a TPMS alarm for anything other than low pressure (which BTW is WAAAY too low and wish I could set it to something higher but with LEAF Spy, its not a big issue)

 

[mjblazin]

I am glad this thread ran. With LeafSpy I can now see the impact of 90 degrees road temps on tire pressure. Based on input here, I now shoot for near 43 and got a little concerned as pressures went 45+.

 

[NeilBlanchard]

I keep the tires at 45PSI and have no problems. Rolls like crazy ...

 

[dhanson865]

I am glad this thread ran. With LeafSpy I can now see the impact of 90 degrees road temps on tire pressure. Based on input here, I now shoot for near 43 and got a little concerned as pressures went 45+.

Sidewall max is in PSI at the coldest point in the day. You don't have to keep it below sidewall max while driving.

If you set it to 44 PSI in the cold of the morning and it goes to 50 PSI in the hot of the afternoon while you are driving 85 mph, that's OK.

 

[DaveinOlyWA]

I am glad this thread ran. With LeafSpy I can now see the impact of 90 degrees road temps on tire pressure. Based on input here, I now shoot for near 43 and got a little concerned as pressures went 45+.

there is no need for worry. the effects of air pressure and heat are not missed with tire manufacturers which is why "cold pressure" is so undefined. it can mean 20º in Minnesota or 85º in Phoenix but what is completely ok is pressures several PSI over your "cold pressure"

 

[NeilBlanchard]

The good news is, that when you start with higher pressure when cold, the tire doesn't warm up as much, and so the delta to warm pressure is reduced. Les flexing in the tire means less heat from friction.

Back when I rode a motorcycle, some advice on tire pressure was to use the cold pressure that had 4-6PSI increase when warm. If you start too low, the increase was greater than that, and if you start too high, the warm pressure only increased a few degrees.

 

[knightmb]

As the subject says, I noticed that when my tire pressure approaches 44 psi (max the tire is rated for), the TPS sensor goes off. I know the TPS is useful to warn against low tire pressure, but how are people running +45 psi in their tires without the constant nag of the TPS sensor warning? Just removing the TPS sensor all-together? I usually run my tires around 38 psi to avoid this (as when it gets hot during the day, the tires seem to gain another 4 or 5 psi from the heat).

Just curious to what others experience here when running high psi to help with hyper-miling. :mrgreen:

your sensors are defective. get them replaced. I ALWAYS run at the max listing on the sidewall in every car I drive. During Summer that usually means pressures hitting 48 -49 PSI. I have never had a TPMS alarm for anything other than low pressure (which BTW is WAAAY too low and wish I could set it to something higher but with LEAF Spy, its not a big issue)

I am running a high psi now and no TPS alarms. Maybe a fluke, but I am starting to wonder if the sensors were getting radio jammed. The alarm always triggered at the same section of road and I always though that my driving and the tires warming was the connection, but I had an instance last week where the tire pressure was still set lower and TPS alarm still went off, but I finally put it together, happens at the same section of road every time.

New question, can the TPS sensors be jammed by something nearby? What frequency do they run on I wonder?

 

[keydiver]

"The TPMS system uses either the 315mhz or 433mhz frequency and does uses encoding but not encyption."
http://www.networkworld.com/article/2231495/cisco-subnet/defcon---hacking-tire-pressure-monitors-remotely.html" onclick="window.open(this.href);return false;

 

[knightmb]

"The TPMS system uses either the 315mhz or 433mhz frequency and does uses encoding but not encyption."
http://www.networkworld.com/article/2231495/cisco-subnet/defcon---hacking-tire-pressure-monitors-remotely.html" onclick="window.open(this.href);return false;

I think 433mhz is used by outdoor weather monitoring? I can understand encryption not being needed, maybe the coded signal gets garbled so that instead of sending "44 psi" the computer hears "4 psi"?

 

[DaveinOlyWA]

jamming implies that someone is not doing what they are supposed to be doing

 

[gbarry42]

"Encoded" implies that the computer can tell a good message from one that's been interfered with.

 

[knightmb]

"Encoded" implies that the computer can tell a good message from one that's been interfered with.

Then no message (say from jamming) might trigger an error. I did a test today. Inflated the cold pressure to 44 psi, drove around town for over 20 miles in the mid-day heat and no problems. Took the vehicle out of town pass that section of road (it follows along a large farm) and sure enough tps warning again. Goes away once I leave the area, turn off vehicle, turn it back on. No more tps errors if I stay away from the area.

 

[GetOffYourGas]

"Encoded" implies that the computer can tell a good message from one that's been interfered with.

Close. Encoded means that the signal is tolerant of some small number of bit errors. You can flip a few bits and the receiver can still figure out what the message was. However, there is a practical limit - you flip enough bits, and the receiver will either get the wrong message, or just give up and assume there is no message.

In order to tell a good message from a bad one typically involves a CRC check which is different from, but complementary to encoding.

 

[knightmb]

Well, been a few days at 44 psi with day time temp at 95F, over 100 miles of city driving in this insane heat + humidity and not a single tps alarm. I am starting to lean towards something at that farm or around it is jamming the tps sensors. What an odd thing to discover about a vehicle, but makes sense. If it is wireless, it can be jammed. :lol:

 

[GetOffYourGas]

Now I'm curious what that farmer is using in that frequency range. Do farmers have remote sensors? Someone mentioned remote weather sensors - maybe they have a high-powered transmitter at the edge of the field, transmitting back to the house or something.

It's definitely an odd thing to discover, but congrats on figuring it out!

 

[Levenkay]

When I was a college student back in the late 1970s, one of my EE proffs was studying the feasibility of sterilizing the top two or three feet of soil of agricultural pests, using tractor-towed powerful downward-pointing microwave energy radiators . Perhaps that practice actually got used? Or maybe the area has something of interest for ground-penetrating radar mapping?

 

[dhanson865]

When I was a college student back in the late 1970s, one of my EE proffs was studying the feasibility of sterilizing the top two or three feet of soil of agricultural pests, using tractor-towed powerful downward-pointing microwave energy radiators . Perhaps that practice actually got used? Or maybe the area has something of interest for ground-penetrating radar mapping?

my first Google hit looking for that was http://www.google.com/patents/US4434345" onclick="window.open(this.href);return false; a scheme for microwaving fruit trees to prevent frost. I don't know that I would want to microwave my fruit on the tree as it grows.