Max Min tire pressure settings in TPMS App

[AV8R]

So we know that Honda recommends for tire pressure for front and back as 42/42 psi.

Now that I have a FoBo TPMS system, the app’s alarm max and min setting requires that I input values. Without knowing better, I entered +/- 10% values, or max of 46 and min of 38 psi. Im running Bridgestones.

“Whats in your wallet?”

 

[STGuy]

So we know that Honda recommends for tire pressure for front and back as 42/42 psi.

Now that I have a FoBo TPMS system, the app’s alarm max and min setting requires that I input values. Without knowing better, I entered +/- 10% values, or max of 46 and min of 38 psi. Im running Bridgestones.

“Whats in your wallet?”

If you are working the tires hard as in load or cornering I would increase the %. On a 10 mile commute in the cold weather my tires come up about 3 pounds. When I filled up tires at 80F ambient and went west no alarms until crossing the Mojave desert with 100F and running 80 mph. I use the alarm for serious leaks and would consider 6 to 8 pounds on the High end and 4 to 6 on the low end. I have two Fobo sets and put them on my kids bikes after a while. I went with a system that has a dash monitor that I can see at all times and keep track of while riding. These I narrowed the alarms to 10%. It's cheaper than a Fobo too. I still use the fobo Tvalves though.

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[AV8R]

Sounds fair.

My riding is typically 4-6 hours in 60 - 95 *F freeway and city driving. Single seat (im a hefty but not fluffy boy), med heavy laden side bags.

So for you road warriors with top boxes, full bags and a passenger, how does that impact these recommended tire pressure specs and tpms range settings?

 

[drrod]

Spirited running, one up but loaded for touring (total about 280 lbs), I saw rear psi reach 54 lbs and front about 50 lbs. Both started at 42 cold (ambient of about 65 degrees in morning but climbing to 80's during the day). The rear also ran 15-20 degrees hotter than the front. At first I thought the TPMS system was off but when checked with a gauge, it was correct. So.....unless you want a constant "hi" warning, I would suggest you set the top limit quite a bit higher than you were going to. The bottom I would leave since it is more important to detect a leak. After all, what are you going to do with a high reading? Stop and bleed air out? I can't help but think that the tire engineers take that into account and their "maximum psi" on the sidewall is for "cold" readings knowing full well that psi may be exceeded in a hot tire.

 

[mortenk]

What everybody else says: the low limit is what counts here. I have set mine to 35 psi, which will give me early warning of slow leaks (like a nail in the tire etc.). I typically see a high of 48 in the winters and 50+ in the summer, which is perfectly normal. I can't even remember what I have set my high warning at - probably 55 or so...

 

[ST Gui]

The bottom I would leave since it is more important to detect a leak. After all, what are you going to do with a high reading? Stop and bleed air out? I can't help but think that the tire engineers take that into account and their "maximum psi" on the sidewall is for "cold" readings knowing full well that psi may be exceeded in a hot tire.

+1 All I care about is tire pressures starting out right and getting low.

 

[CYYJ]

I would not be concerned about setting any kind of upper pressure limit - in my lifetime, I have never encountered a tire that gains air pressure (other than the usual temporary increase in pressure that happens when the motorcycle is ridden and the tire temperature increases).

I suggest you set a lower limit of 38 PSI, which is what I use. That's 4 PSI below spec. That gives 4 PSI of "wiggle room" to allow for lower pressure that temporarily arises due to colder than average ambient temperature, or the very slow loss of air pressure that seems to happen with every tire (by this I mean a loss of 1 PSI per month or less).

38 PSI works for me - I don't get alerts caused by parking outside overnight on a cold night, and when I do get an alert, the pressure drop has been large enough to warrant me doing something about it (re-inflating the tire), or investigating for cause (looking for something that has punctured the tire).

Michael

 

[Al Gully]

I see your running Bridgestones, The stickers on my new T31 GT's in the garage say never exceed 57 psi, you can use that as high limits.
I've seen 52 psi running 80 mph on I-5 in CA. Outside air temperature was 103 F.

 

[AV8R]

Gully,

I’ll be more conservative and set the max to 55 psi
Did you put TPMS on your bike trailer too?
FoBo has a product for that.

 

[SMSW]

I use a 39 low limit and I don't remember the upper. I set my pressure to 42 +/- 1/2 lb before I leave the house (if it needs adjusting) and have seen it go up to 50 in the rear. Since we have no control over the pressure gain, as long as the tires start out cold at 42, whatever the rise really doesn't matter. (And if the tire explodes, you will get the low pressure alarm in plenty of time to contemplate why that happened.)

I chose 39 because I want the Fobo to regularly show me an alert as a check the system is functioning. So far it mostly signals a problem if the bike sits for more than a couple of weeks.

 

[Al Gully]

AV8R
No, I only used the Orange system on the 2 tires. I'll look into the FoBo system.
Wife has a F3 Spyder with 3 wheels also. It's a reverse trike.

 

[AV8R]

So it’s “normal” even for a new tire to leak a few pounds just sitting or riding over a week or so?

 

[ST Gui]

This, from a desert dweller where temps often hover at 120 degrees.

Much respect! Long before 120º I'm indoors in front of a fan or in A/C sipping a lemonade. A fair weather rider has upper limits too and a reputation to uphold!

 

[STGuy]

So it’s “normal” even for a new tire to leak a few pounds just sitting or riding over a week or so?

Not for me. But over a couple of months yes. Ambient temperature has a much greater effect. Temps dropped from 65 to 70 lately to 35 to 50*F and both my tires were at 29#'s. My daughters were also down about 10# each.

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[mortenk]

When you say "leak a few pounds" make sure you are checking at the same temperature each time. If the ambient temperature e.g. dropped 30 deg in the past few weeks, then yes, you would expect to see your cold tire pressure to follow that trend - simply because the tire is colder...a good rule of thumb: tire pressure changes with about the same percentage as the temperature changes (using Kelvin as the temperature scale). 300 degree Kelvin is a nice summer ambient temperature (approx. 80 degF) - let's assume you calibrated pressure to 42 psi. If the temperature drops by 10% you land just below freezing, and at that temperature your tire would probably be 10% lower (e.g. 38 psi). As a result I add air to the tires a lot more often in the fall compared to the spring. And finally: I do seem to lose some air over time regardless of temperature. Not sure if the valve or tire "seal" is to blame...but it happens on all my vehicles

 

[dwalby]

...a good rule of thumb: tire pressure changes with about the same percentage as the temperature changes (using Kelvin as the temperature scale). 300 degree Kelvin is a nice summer ambient temperature (approx. 80 degF) - let's assume you calibrated pressure to 42 psi. If the temperature drops by 10% you land just below freezing, and at that temperature your tire would probably be 10% lower (e.g. 38 psi). As a result I add air to the tires a lot more often in the fall compared to the spring.

I know its splitting hairs, but the pV=nRT relationship would refer to absolute pressure, not gauge pressure. In other words, instead of taking 10% of 42psi (gauge), you'd take 10% of 57psi (absolute), so it would drop 1.5psi more than you suggested.

 

[drtyrrel]

Expect to lose about a pound each time you put the tire gauge on it.

 

[STGuy]

I know its splitting hairs, but the pV=nRT relationship would refer to absolute pressure, not gauge pressure. In other words, instead of taking 10% of 42psi (gauge), you'd take 10% of 57psi (absolute), so it would drop 1.5psi more than you suggested.

That is an equation that I haven't seen in 15 years!

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[AV8R]

Since physics engineering Uni.... 1980-ish

 

[AV8R]