Need advice on setting TPMS alarms

[WackAway]

I just got a Carchet TPMS System for my 5'r which has max/min alarms for pressure and a max temp alarm. What would be good settings for these alarms given a load rating E tire? Baseline pressure is 80 psi cold (70 degrees). The sensors screw onto the stems, so I do realize the temperature readings probably are not close to inside tire temps.

Max Pressure = ?
Min Pressure = ?
Max Temperature = ?

Thanks in advance

[WackAway]

ken burke wrote:


My tire monitor used to make alarms. So I finally gave in and read the instruction. Have your wife read the instructions.

That would be like asking for directions. Arggggg!

[ken_burke]

WackAway wrote:
I just got a Carchet TPMS System for my 5'r which has max/min alarms for pressure and a max temp alarm. What would be good settings for these alarms given a load rating E tire? Baseline pressure is 80 psi cold (70 degrees). The sensors screw onto the stems, so I do realize the temperature readings probably are not close to inside tire temps.

Max Pressure = ?
Min Pressure = ?
Max Temperature = ?

Thanks in advance

My tire monitor used to make alarms. So I finally gave in and read the instruction. Have your wife read the instructions.

[Ohio_Engineer]

From a tire standpoint...
You do not want to drive on a tire that has less air than needed to carry the actual load. You can also avoid getting readings from your TPMS if you ensure the Cold Inflation Pressure CIP is above the minimum.

Soooo
1. Knowing the actual load on each tire I know the minimum inflation needed based on the heavier end of each axle.

2. The CIP is the minimum + 10%. This gives a nice cushion when the temperature drops a few degrees. At 2% change for each 10F change if you see a 50F change in ambient you probably need to make an inflation change.

3. The low pressure warning level should be the minimum inflation needed to carry the load. Good TPMS will provide early warning if the tire looses a few psi from the running hop pressure and not only warn when a tire gets down to the set warning level.

4. You will probably find a +25% above the CIP adequate for high pressure warning BUT normally that will not be a problem.

5. The 158F high temp is also a reasonable number.

[cmeade]

This probably won't help but I run 65 psi in front and 75 psi rear and 80 psi in all 5ver tires. Witn home temps at 95 degrees we went to Ft Bragg CA for a week with 48 degree nites. Alarms set at 55 psi front, rear at 70 psi and 5ver at 65 psi. First morning sightseeing had warnings on TV tires and had to air them up for sanity sake as all tires had warnings. When we hooked up to go home the 5 ver needed air to shut off alarms.

[Beverley_Ken]

bob213 wrote:
When I got my 1st TST there was an additional sheet that recommended 20 per cent above max (or normal running pressure) and 10 per cent below. I still use those percentages's.

Same here,
After taking the sensors off a couple of times to check the pressure , and getting the same readings as the sensors, I know rely on the sensors. Turn system on wait a few minutes and check from the drivers seat. I still do a visual check when doing the walk around.

Ken

[bob213]

When I got my 1st TST there was an additional sheet that recommended 20 per cent above max (or normal running pressure) and 10 per cent below. I still use those percentages's.

[RustyJC]

Sam Spade wrote:

RustyJC wrote:

With a cold inflation pressure of 80 PSIG, I'd start with max pressure = 95 PSIG,

I agree with setting the pressure loss alarm at -10.

But if you set the increase alarm as above, or at any pressure really, what does it MEAN if you go over that.....and what will you do about it ??

Same thing for temp. increase......unless maybe only ONE tire consistently gets a LOT hotter than all the others, but you don't need an alarm to see that.

I set my TPMS system up on the pressure side based around the normal operating profile for my tires. On a cold morning, inflation pressure might be slightly under the cold inflation pressure when I last inflated the tires. After 3 hours on the Interstate on a hot day, I've seen pressures of 142-143 PSIG on our Goodyear G114s after starting out at 120 PSIG. Therefore, I'll set my high pressure alarm around 147 PSIG - if any tire has more pressure buildup than normal or than the other tires, I want to know it so that I can stop and check it out.

The 158 degF alarm setting on temperature is FAR outside the normal operating range of my tires, but according to TST that's their factory setting and recommended setting based on the advice of tire engineers who stated that degradation leading up to failure can occur at temperatures above that level.

If you don't want to know about high pressure or temperature, then set those alarm points as high as they will go.

Rusty

[2oldman]

WackAway wrote:
I still will be using the good 'ole hand-held "pressure-thing-o-mometer". 🙂

Assuming you mean the analogue kind you stick on the valve stem, you'll likely quit doing that after you trust the unit to be correct, and you get tired of having to take off the sensors. I didn't see that they were the 'pass through' kind.

[WackAway]

All good points. The main functionality I will look for is going under-pressure and rapid pressure decrease whle driving. This unit will do that supposedly well. The other data points, like you said are most interesting if they are unbalanced.

I still will be using the good 'ole hand-held "pressure-thing-o-mometer". 🙂

[Sam_Spade]

RustyJC wrote:

With a cold inflation pressure of 80 PSIG, I'd start with max pressure = 95 PSIG,

I agree with setting the pressure loss alarm at -10.

But if you set the increase alarm as above, or at any pressure really, what does it MEAN if you go over that.....and what will you do about it ??

Same thing for temp. increase......unless maybe only ONE tire consistently gets a LOT hotter than all the others, but you don't need an alarm to see that.

[RustyJC]

You'll find that it's somewhat of a trial-and-error process as the operating characteristics of your tires will depend on the construction of the tires (all steel construction tires tend to run cooler), load, speed, ambient conditions, etc.

With a cold inflation pressure of 80 PSIG, I'd start with max pressure = 95 PSIG, min pressure = 70 PSIG and max temperature = 158 degF (the latter is recommended by TST based on consultation with tire industry engineers). Then adjust as required.

Rusty

[garyemunson]

Our Class A calls for 90 psi cold. I check it on cold mornings and have the alarm set for 80. Since I'm always starting out at 90, if the alarm goes off, it's pretty likely something is wrong. I have the display in an easy to see location and make it a habit to glance at it on a regular basis. MUCH more peace of mind than routinely getting the tire gauge out (and not being sure if you picked up a nail right after you checked pressure).

[Sam_Spade]

Well this should be interesting.

IMHO, that kind of a system is WAY too complicated because it gives users too much latitude to do unwise things.

For instance, as long as you can SEE the current pressure on the display, there is really no good reason to constantly monitor pressure increases.