Question Tire Monitor from Tire Minder

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Joined
Nov 19, 2019
Messages
113
Location
Kansas
RV Year
2017
RV Make
Newmar
RV Model
Ventana LE
RV Length
40
TOW/TOAD
2020 Jeep Rubicon
We have the new Tire Minder system and to set the low and high pressure it uses 20% above and 15% below the preferred cold pressure setting. We set our rear tires to 95 PSI which gives us a high-pressure warning of 114 PSI and low pressure warning 89 PSI. Going a short 50-mile trip to get the oil changed the high-pressure warning went off on both inside rear tires with a pressure of 117 and the outside duals were running at 112. Both of our front tires were set at 105 cold and were just a couple of pounds below the high pressure warnings. The outside temp was about 70 degrees so in 100-degree weather in Texas this summer these settings are not going to work. According to Tire Minder with 95 PSI you should get less than 19 PSI increase in tire pressure.
What kind of pressure swings are you seen from say morning temp of 75 degrees and afternoon temp of 100-afternoon temps driving down an asphalt road?

Here is a pic of the new Tire Minder. The NS on the bottom is because I don't have my jeep hooked up.
 

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Joined
Nov 2, 2019
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WA, MT or somewhere else!
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2018
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Newmar
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Mountain Aire 4047
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2014 Honda CR-V
Not familiar with the Tire Minder system, but on our EEZTire unit, the high-pressure alarm is set at 20% above cold setting and the low-pressure setting is 10% below. We have never had an over or under alarm on our unit. In some fairly hot weather. We have come within 5-10 pounds of the limit on occasion.

I don't understand why you are getting alarms in 75-degree weather. Are you sure you have the reference (cold) pressures set correctly?

If all is set correctly, I would be on the phone to the manufacturer.

TJ
 
Joined
Nov 15, 2019
Messages
188
Location
Portage, MI
RV Year
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Newmar
RV Model
Ventana LE 4037
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40' 11"
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2021 Chevy Trailblazer
I use a different TPMS, but it shouldn’t matter. I started out at +15% and that was too low for the 80 degree ambient at that time. I kept nudging the high alarm until it did not alarm, fully knowing that the tires were OK. After a couple hundred, maybe a thousand miles I ended at +23% on the fronts and +20% on the rears.
I was quite amazed at the pressure and temperature gain. Now with several thousand miles at those high alarm levels, I’m OK. The gain is very consistent day to day.
According to the CAT weights and Michelin tables I’m at 130 fronts and 120 rears.
 
Joined
Nov 19, 2019
Messages
113
Location
Kansas
RV Year
2017
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Newmar
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Ventana LE
RV Length
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2020 Jeep Rubicon
I use a different TPMS, but it shouldn’t matter. I started out at +15% and that was too low for the 80 degree ambient at that time. I kept nudging the high alarm until it did not alarm, fully knowing that the tires were OK. After a couple hundred, maybe a thousand miles I ended at +23% on the fronts and +20% on the rears.
I was quite amazed at the pressure and temperature gain. Now with several thousand miles at those high alarm levels, I’m OK. The gain is very consistent day to day.
According to the CAT weights and Michelin tables I’m at 130 fronts and 120 rears.
I also have a 2017 Newmar Ventana LE and run the front at 105 and the rear at 95 and tires are 275/70R22.5. The chart below gives me a axle weight of
 
Joined
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Messages
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Kansas
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Newmar
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Ventana LE
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2020 Jeep Rubicon
Randy
I run my front tires at 105 based off a CAT scale weight of 11,450 and see you are running 130 that base of 13,880 Michelin table weight with front axle GAWR of 13,500.

I run my back duals at 95 with a scale rating of 19,400 and I see you running 120 which has a Michelin table weight of 24,000 pounds with a GAWR 24,000 axle rating.

I running light last year and still running light but we have to scale again before heading to Tucson in a few days. I expect I will have to go probably 10 pounds all the way around. Still only 115 front and 105 rear. You must be running very close to your max GVWR with those pressures. Here is the chart I'm using and the link to the chart
Using tire size of 275/70R 22.5

1583545406626.png
 
Joined
Nov 15, 2019
Messages
188
Location
Portage, MI
RV Year
2017
RV Make
Newmar
RV Model
Ventana LE 4037
RV Length
40' 11"
TOW/TOAD
2021 Chevy Trailblazer
FD1FDD8E-8701-4C05-8195-12FC375C5549.png

my worksheet.
 
Joined
Nov 19, 2019
Messages
113
Location
Kansas
RV Year
2017
RV Make
Newmar
RV Model
Ventana LE
RV Length
40
TOW/TOAD
2020 Jeep Rubicon
Isn't that Newmar chart figuring MAX weights? There isn't any allowance for running well under the rated capacity of the axles/tires.

Locks like to me you should be running 120 front and 100 rear using the chart from Michelin

Someone please correct me if I'm wrong - I'm still newbie with Class As
 
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Joined
Nov 15, 2019
Messages
188
Location
Portage, MI
RV Year
2017
RV Make
Newmar
RV Model
Ventana LE 4037
RV Length
40' 11"
TOW/TOAD
2021 Chevy Trailblazer
While I can see your point about running a lower tire pressure based on weights, I would offer that the weights are actual and do not factor into consideration any margin. The front axle for example is just less than 8% under weight. In the grand scheme of things, to me, that is approaching insignificant. A little more load here and there and I'd be at the max axle weight. I also recall reading from RVers that have been in the game far longer advising to factor in about 5% of actual weight when consulting the tire limit charts. So, even though the pressures seem too high at first glance, I am OK with them where they are.

It is my belief that under-pressured tires will have a higher percentage of pressure gain from cold to operating temps. That being said, I do not think that over-pressured tires have less gain than properly pressured tires. I tend to pressure all my tires on the higher side by a few PSI.

Getting back to the original post: "What kind of pressure swings are you seen from say morning temp of 75 degrees and afternoon temp of 100-afternoon temps driving down an asphalt road?" My point to the original question is that yes, I am seeing higher pressure gains. My hidden advice was that raising the high alarm thresholds is likely necessary.

Chart for the XZE is a little different than the one posted above
1583589451444.png


Update: after consideration of the advice to reduce the target pressures, I did. I had a 200 mile relocation run. About 3/4 of it on interstates. Started out at ambient temps of 58 ended at 64.
Set front pressures at 125. Rose to a high of 148, for a 18.4% increase.
Set all 4 rears to 100 and got up to 18 for an 18% increase.
The ride seemed to be a bit smoother. Not quite as harsh on the little chatter bumps. I’ll try it on the next leg of our trip which is 2,000 towards home.
My verbiage now reads a bit snarky in previous posts. It was not intended. My apologies and thanks for giving me something to consider.
 
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