Will the R1300GS have temperature adjusted TPMS?

[ekullmann]

I was just educated on another forum.
Apparently the reason my TPMS system is so inaccurate is because the system corrects for temperature. I hate it. Its on page 48 of the paper manual if you dont believe me. I didnt believe it either. I hate it.
Does anyone know if the 1300 will continue this nonsense?

 

[r0ckrat]

Why do you assume that the TPMS is inaccurate if it is correcting for temperature? If you aren't manually correcting your un-corrected measurements for temperature, aren't they inaccurate?

(Mostly tongue in cheek comment above...)

I doubt they will change the system, as it's the in-tire sensors that are doing all the math...

 

[kthutchinson]

"I doubt they will change the system, as it's the in-tire sensors that are doing all the math..."

I think the math is done on-board. The sensors report their pressures and temperatures, and the bike does the conversion.

 

[lee]

Does anyone know if the 1300 will continue this

BMW has used this TPM setup for a long time. I would be surprised if they changed now.

 

[r0ckrat]

Additionally, from a little research, TPMS systems of some sort are required on all vehicles (since 2006.)

 

[pglaves]

If a person has a properly operating temperature corrected TPMS system, unless the tire/wheel is at 20C (68F) the system will not match what a typical accurate pressure gauge will read. I forget the formulas for Boyle's Law and Charles' Law but if I recall generally, a 10 degree F change in temperature will result in an approximate 1 psi change in contained pressure. A good TPMS system will display the current measured pressure corrected to a standard temperature which by convention is normally 20C (68F)

Where I ride in the spring/summer/fall I will often find a 20 to 30 degree increase in tire air temperature once the tire has warmed up. With a correct gauge I would see a 2 to 3 psi increase in pressure. But with a temperature corrected TPMS I would see very little change on the display. Now this is "perfect world" stuff so measurements and displays might be a psi or so off.

In an imperfect world with a crappy TPMS system things might appear differently but the above is how the systems are supposed to work.

 

[MCMXCIVRS]

I had a recent experience riding a different brand of motorcycle which did not use temperature correction for it's TPMS. Over the length of the tour, we went through a lot of varying conditions - both weather and road. All would be fine with the TPMS, then a small change in conditions would result in a change in the tire pressure and the system would pop up a warning. That would soon go away only to reappear later when things changed again. It was incredibly annoying to have to keep cancelling the warning prompt on the screen. The tires were always inflated within specs, so this was just a reaction by the system to the change. BMWs temperature correcting system seems a better choice.

 

[rhbike]

Why do you assume that the TPMS is inaccurate if it is correcting for temperature? If you aren't manually correcting your un-corrected measurements for temperature, aren't they inaccurate?

(Mostly tongue in cheek comment above...)

I doubt they will change the system, as it's the in-tire sensors that are doing all the math...

The TPMS reports temp and pressure. The math is done by a BMW module.

 

[kthutchinson]

"Additionally, from a little research, TPMS systems of some sort are required on all vehicles (since 2006.)

Not on motorcycles.

 

[Omega Man]

I was just educated on another forum.
Apparently the reason my TPMS system is so inaccurate is because the system corrects for temperature. I hate it. Its on page 48 of the paper manual if you dont believe me. I didnt believe it either. I hate it.
Does anyone know if the 1300 will continue this nonsense?

I have read many (all) of the TPMS threads here on the forum. I don't understand the "hate" for something that is really an improvement over watching a tire pressure, possibly setting off a warning, rise and fall all day due to the rise and fall of ambient temperature?

If a person has a properly operating temperature corrected TPMS system, unless the tire/wheel is at 20C (68F) the system will not match what a typical accurate pressure gauge will read. I forget the formulas for Boyle's Law and Charles' Law but if I recall generally, a 10 degree F change in temperature will result in an approximate 1 psi change in contained pressure. A good TPMS system will display the current measured pressure corrected to a standard temperature which by convention is normally 20C (68F)

Where I ride in the spring/summer/fall I will often find a 20 to 30 degree increase in tire air temperature once the tire has warmed up. With a correct gauge I would see a 2 to 3 psi increase in pressure. But with a temperature corrected TPMS I would see very little change on the display. Now this is "perfect world" stuff so measurements and displays might be a psi or so off.

In an imperfect world with a crappy TPMS system things might appear differently but the above is how the systems are supposed to work.

^^^A rather educated in-depth explanation. ^^^

I had a recent experience riding a different brand of motorcycle which did not use temperature correction for it's TPMS. Over the length of the tour, we went through a lot of varying conditions - both weather and road. All would be fine with the TPMS, then a small change in conditions would result in a change in the tire pressure and the system would pop up a warning. That would soon go away only to reappear later when things changed again. It was incredibly annoying to have to keep cancelling the warning prompt on the screen. The tires were always inflated within specs, so this was just a reaction by the system to the change. BMWs temperature correcting system seems a better choice.

^^^The way I look at it. It's a feature not found in/on other brands of motorcycles.^^^

The "add-on" valve stem located system on my motorhome displays both the pressure and the temperature and on a hot day, I have seen the temperature rise as much as 17psi after hot, highway driving......which is expected. There is no alarms set off as this is an anticipated, reaction. There is an alarm for low pressure which generally indicates trouble.

"Temperature compensation aims to negate or minimize the impact of temperature variations on sensor output. A temperature-compensated sensor will provide consistent readings across its specified temperature range".

OM

 

[kthutchinson]

I've had several cars with TPMS (mandatory in the US since 2008). Some displayed tire pressures, and some only had an idiot light. In those that displayed pressures, none used the kind of temperature compensation BMW uses on their motorcycles; they all displayed the actual pressure, which rose with temperature while driving. I find this a better indication of how the tire is behaving than a fixed value. If the pressure rise is too great, the tire is probably overheating. To solve this problem on my 2007 R1200ST I added tire temperature to the available readouts on the trip meter.

 

[oldcamper]

Psi in a tire is a pressure differential to the current barometer reading outside the tire. Although air pressure in a closed body (like a tire) will vary with the air temperature in that body, a pressure gauge should reflect that. If a gauge doesn’t report psi correctly at different temperatures, it’s poorly designed. I can understand that a TPM alarm function may be tied in with temperature to avoid false alarms when the air is cold.

 

[marcopolo]

I have no issue whatsoever with BMW's TPMS. As for the original question, I took a look at 1300 GS rider's manual. The TPMS remains temperature compensated.

 

[mneblett]

Correct me where I go wrong here:

Let's say I have a bike with tires properly inflated to 36F/42R when the ambient temperature is 68F.

Now let's start riding when the ambient temperature is 28F (some of us actually do this, but here 28F is chosen just for convenient math).

So at the start of the cold ride, actual pressure in the tires is 32F/38F -- 4 psi low. But the BMW system tells me the pressures are 36F/42R.

So the BMW system appears to be "ok" with me riding around on under-inflated tires when the ambient temperature is below 68F (with the accompanying tire profile, wear and handling degradations).

This is why I *much* prefer actual pressure read-outs: they let me immediately know whether I need to add/remove air to suit conditions, without having to pull out a manual pressure gauge before each ride -- something necessitated by the BMW TPMS because isn't telling me the current pressure (the alternative is to just not check, but I'm not keen on the "ignorance is bliss" approach to tire pressure).

This is all the more an issue if I don't know what the current temperature is to any more accurate a level than "it's cold," because the BMW system does not tell me by how much it has corrected the current pressures.

In addition, by getting actual pressure reports I can judge whether the tire temperatures are in the right ballpark, vs. potentially being overloaded. If the pressure in warmed-up tires has gone up roughly 2-3 psi at speed, I know the tires are coping with the current vehicle weight (e.g., not overheating due to the current load). BMW's temperature compensation also eliminates this useful information, as a temperature rise of, say, 10F (indicating under-inflation for the current load), would still result in the temperature-corrected pressure being the pressure at 68F.

In contrast, my Gold Wing tells me exactly what I need to know without any mental gymnastics: the actual pressure in the current conditions (ambient and loading). This is far superior IMO, as I immediately know whether I need to take appropriate action.

Obviously, I'm not a fan of BMW's approach.

An aside: The conspiracy theory part of me is guessing that BMW picked this approach because too many unknowledgeable people complain when they see any change in pressure -- similar to Ford's at one point having used oil pressure instruments which show a range but only go to the same pressure every time (unless the oil pressure had dropped to zero) -- an approach which resulted in fewer customer service visits due to people thinking oil pressure had dropped "dangerously" too low when the engine dropped down to idle.

I've yet to hear directly from BMW exactly what is their reason(s) for the current TPMS approach -- I would *love* to hear from the mothership.

As I said above, if I've missed something, please enlighten me. For the moment, though, I still believe BMW's TMPS temperature-correction approach unnecessarily complicates an otherwise very clear concept, and it could lead to potential tire underpressure- and/or overheating-related problems.

 

[pglaves]

Correct me where I go wrong here:

Let's say I have a bike with tires properly inflated to 36F/42R when the ambient temperature is 68F.

Now let's start riding when the ambient temperature is 28F (some of us actually do this, but here 28F is chosen just for convenient math).

So at the start of the cold ride, actual pressure in the tires is 32F/38F -- 4 psi low. But the BMW system tells me the pressures are 36F/42R.

So the BMW system appears to be "ok" with me riding around on under-inflated tires when the ambient temperature is below 68F (with the accompanying tire profile, wear and handling degradations).

This is why I *much* prefer actual pressure read-outs: they let me immediately know whether I need to add/remove air to suit conditions, without having to pull out a manual pressure gauge before each ride -- something necessitated by the BMW TPMS because isn't telling me the current pressure (the alternative is to just not check, but I'm not keen on the "ignorance is bliss" approach to tire pressure).

This is all the more an issue if I don't know what the current temperature is to any more accurate a level than "it's cold," because the BMW system does not tell me by how much it has corrected the current pressures.

In addition, by getting actual pressure reports I can judge whether the tire temperatures are in the right ballpark, vs. potentially being overloaded. If the pressure in warmed-up tires has gone up roughly 2-3 psi at speed, I know the tires are coping with the current vehicle weight (e.g., not overheating due to the current load). BMW's temperature compensation also eliminates this useful information, as a temperature rise of, say, 10F (indicating under-inflation for the current load), would still result in the temperature-corrected pressure being the pressure at 68F.

In contrast, my Gold Wing tells me exactly what I need to know without any mental gymnastics: the actual pressure in the current conditions (ambient and loading). This is far superior IMO, as I immediately know whether I need to take appropriate action.

Obviously, I'm not a fan of BMW's approach.

An aside: The conspiracy theory part of me is guessing that BMW picked this approach because too many unknowledgeable people complain when they see any change in pressure -- similar to Ford's at one point having used oil pressure instruments which show a range but only go to the same pressure every time (unless the oil pressure had dropped to zero) -- an approach which resulted in fewer customer service visits due to people thinking oil pressure had dropped "dangerously" too low when the engine dropped down to idle.

I've yet to hear directly from BMW exactly what is their reason(s) for the current TPMS approach -- I would *love* to hear from the mothership.

As I said above, if I've missed something, please enlighten me. For the moment, though, I still believe BMW's TMPS temperature-correction approach unnecessarily complicates an otherwise very clear concept, and it could lead to potential tire underpressure- and/or overheating-related problems.

My simple answer is I don't think the tires are underinflated in your scenario. Specified or recommended pressure is at 20C. The pressure will then fluctuate up and down with temperature but if it is or would still be as specified at 20C that is correct inflation.

 

[Omega Man]

Pretty sure it’s just two different systems.
Tire pressure is supposed to be adjusted “cold”.
Cold is factored as-
Tires are considered cold when the vehicle has been parked for three hours or more, or if the vehicle has been driven less than a mile (1.6 km) at moderate speed.
Leaving on a 28* morning with the later temperature approaching 80* will always show an increase of tire pressure.
I probably have 48 tires mounted here and having read the tire pressures moulded into the tire, none have ever mentioned adjusting tire pressure during a days activity.
Never seeing anything but a “cold” recommendation, the tire manufacturers have to be aware of of this and tire construction is taken into consideration.
Seems like just two different systems and as long as the rider is aware, ride on.
OM

 

[tsconver]

Correct me where I go wrong here:

Let's say I have a bike with tires properly inflated to 36F/42R when the ambient temperature is 68F.

Now let's start riding when the ambient temperature is 28F (some of us actually do this, but here 28F is chosen just for convenient math).

So at the start of the cold ride, actual pressure in the tires is 32F/38F -- 4 psi low. But the BMW system tells me the pressures are 36F/42R.

So the BMW system appears to be "ok" with me riding around on under-inflated tires when the ambient temperature is below 68F (with the accompanying tire profile, wear and handling degradations).

This is why I *much* prefer actual pressure read-outs: they let me immediately know whether I need to add/remove air to suit conditions, without having to pull out a manual pressure gauge before each ride -- something necessitated by the BMW TPMS because isn't telling me the current pressure (the alternative is to just not check, but I'm not keen on the "ignorance is bliss" approach to tire pressure).

This is all the more an issue if I don't know what the current temperature is to any more accurate a level than "it's cold," because the BMW system does not tell me by how much it has corrected the current pressures.

In addition, by getting actual pressure reports I can judge whether the tire temperatures are in the right ballpark, vs. potentially being overloaded. If the pressure in warmed-up tires has gone up roughly 2-3 psi at speed, I know the tires are coping with the current vehicle weight (e.g., not overheating due to the current load). BMW's temperature compensation also eliminates this useful information, as a temperature rise of, say, 10F (indicating under-inflation for the current load), would still result in the temperature-corrected pressure being the pressure at 68F.

In contrast, my Gold Wing tells me exactly what I need to know without any mental gymnastics: the actual pressure in the current conditions (ambient and loading). This is far superior IMO, as I immediately know whether I need to take appropriate action.

Obviously, I'm not a fan of BMW's approach.

An aside: The conspiracy theory part of me is guessing that BMW picked this approach because too many unknowledgeable people complain when they see any change in pressure -- similar to Ford's at one point having used oil pressure instruments which show a range but only go to the same pressure every time (unless the oil pressure had dropped to zero) -- an approach which resulted in fewer customer service visits due to people thinking oil pressure had dropped "dangerously" too low when the engine dropped down to idle.

I've yet to hear directly from BMW exactly what is their reason(s) for the current TPMS approach -- I would *love* to hear from the mothership.

As I said above, if I've missed something, please enlighten me. For the moment, though, I still believe BMW's TMPS temperature-correction approach unnecessarily complicates an otherwise very clear concept, and it could lead to potential tire underpressure- and/or overheating-related problems.

Your assumptions are completely wrong.

To be absolutely clear if you set your tires to 38/42 at 28 degrees F they are overinflated per the tire manufacturer and if you set them to 38/42 at 100 degrees F they are underinflated.

The 38psi and 42psi are the tire pressures at 25 Celsius or 68 F. All tire pressures on the sides of tires are at that standard temperature. The correct pressure is based on temperature. If it is 0 degrees out then you need less pressure in the tire to meet the manufacturer spec. And if it is 100 out you need more pressure. It is based on PV=nRT. It comes out to be about 2 psi per 10 degrees F change. There are tables out there with the conversions.

By a cheap TPMS wake up tool. Then turn on your bike wake up the TPMS and set the tire to the exact pressure of either 38 or 42 using the cluster and ride off. Or pull up to a gas station with tires that are at full operating temp and again set them to 42 or 38 using the cluster and they will be correct.

The system works really well as is.


https://www.amazon.com/JDIAG-EL-504...a7bqGcXi536BAt2lRpE0NRKGloRoCRssQAvD_BwE&th=1

 

[brownie0486]

68F = 36/42
98F = 39/45
38F = 33/39

1 # of pressure up or down for every 10F difference from the 68F. Here in the desert when it's 115F here which makes the garage about 98F, I'll set the tires at 39/45. My tpms will show 37/43 [ as they are always off by 2F [ usually lower by two ].

How do I know that? I set the tires when the garage is exactly 68F to 36/42. I get on the bike and go ride it. The tpms shows 34/40. So mines off by 2F. Knowing this, when I check the tpms whenever I'm riding, whatever the numbers are, I subtract 2F and I know that's the tires pressure.

tsconover is spot on.

 

[mneblett]

Your assumptions are completely wrong.

To be absolutely clear if you set your tires to 38/42 at 28 degrees F they are overinflated per the tire manufacturer and if you set them to 38/42 at 100 degrees F they are underinflated.

The 38psi and 42psi are the tire pressures at 25 Celsius or 68 F. All tire pressures on the sides of tires are at that standard temperature. The correct pressure is based on temperature. If it is 0 degrees out then you need less pressure in the tire to meet the manufacturer spec. And if it is 100 out you need more pressure. It is based on PV=nRT. It comes out to be about 2 psi per 10 degrees F change. There are tables out there with the conversions.

By a cheap TPMS wake up tool. Then turn on your bike wake up the TPMS and set the tire to the exact pressure of either 38 or 42 using the cluster and ride off. Or pull up to a gas station with tires that are at full operating temp and again set them to 42 or 38 using the cluster and they will be correct.

The system works really well as is.


https://www.amazon.com/JDIAG-EL-504...a7bqGcXi536BAt2lRpE0NRKGloRoCRssQAvD_BwE&th=1

With respect, I believe you are wrong.

The manufacturers set tire pressures to, among other things, establish an optimum tire cross-section profile to obtain a desired contact patch. Per thermodynamics (PV=nRT), tires with 36/42 psi at 68F will have pressures at ~32/38 psi at 28F -- in other words, at pressure levels which do not hold the tire sidewall as "tall" as at 68F, thereby distorting the profile and increasing sidewall flexing due to the reduced air pressure support of the tire carcass.

If I'm at 28F at the start of a ride, I'll inflate the tires to 36/42 psi to maintain the as-designed tire profile. If I later find myself at in an environment which will stay around 68F (e.g., shifting from winter to spring, or going from mountains down into Death Valley), I'll bleed off some air to reset the pressures to 36/42 psi at the then-current temperature.

Think back to the days before TPMS systems: We'd all set the pressure to the recommended level (e.g., 36/42 psi) at whatever temperature we were currently standing in -- nobody stood there calculating how much they should reduce or increase pressure to reach the 68F pressures.

The old way always resulted in the manufacturer's desired tire profiles, without, for example, the potential for a heavily-loaded rear tire that is under-inflated at 38 psi to be subject to detrimental excess heat from increased sidewall flexing.

I still maintain that the BMW approach to TPMS has created unnecessary confusion in what was a simple subject (witness the amount of keyboard warrior energy that has been generated by BMW's choice). If the system reported actual pressures none of this "what is the actual pressure" calculation foolishness would be necessary.

 

[r0ckrat]

Think back to the days before TPMS systems: We'd all set the pressure to the recommended level (e.g., 36/42 psi) at whatever temperature we were currently standing in -- nobody stood there calculating how much they should reduce or increase pressure to reach the 68F pressures.

The old way always resulted in the manufacturer's desired tire profiles, without, for example, the potential for a heavily-loaded rear tire that is under-inflated at 38 psi to be subject to detrimental excess heat from increased sidewall flexing.

With respect, I believe you are over-thinking it and assuming that "the old ways" were better.

At 28F, the external air (what's pressing on the outside of the tire) is also of a lower density, thereby requiring a lower internal pressure to maintain the tire shape. However, while riding in 28F weather, the internal air temperature of the tire is still going to be higher than that external 28F, due to road friction and flexing of the tire carcass.

The only reasons I can see being a factor in deviating from the published tire pressures are running outside of the general use guidelines, like extreme loads, track use (or similarly riding extremely hard), or off road. Adding a PSi or 3 for higher loads, adjusting PSi for specific wear patterns when track-style riding, or lowering for some off-road terrains would then be an adjustment to the baseline recommended by the TPMS system for those extreme conditions.