Kawasaki Concours Forum
The C-14, aka Kawasaki Concours-14, the new one :) => The Bike - C14/GTR 1400 => Topic started by: So Cal Joe on July 31, 2011, 05:32:02 PM
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I always check my tire pressure before I ride my bike, a short time back someone posted a different way to check them. Something about checking them cold and then running them for 15 minutes and checking them again, if they were over so many pounds you added air or if they were over a greater amount you let a pound or two out. Anyone have a link to this post, I want to try it.
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Isn't it just supposed to be 42 cold?? ???
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Isn't it just supposed to be 42 cold?? ???
That is my understanding, also. When I do check pressures, I always use a quality, dial-indicator type meter. Life is too short to waste money on crappy meters (and there are a LOT of them out there).
I am not pleased that the TPS "temperature adjusts" because I can't remember what it is doing. I would prefer it told me what the actual pressure was. I am not stupid, I know the pressure will go up as the tires get hot. It is just like yesterday, I had been riding 30 min and looked at the pressures and it said "40". So I have to think "hmmm... is that 40 for real or some pseudo-40? It should be something like 45 or 46 now." Either way, it is low... will check with the real meter before next ride.
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Kind of.... the problem is what is 'cold'? I believe that the nominal cold is 20C or 68F. If you fill a tire to, say, 42 PSI when it is 90F outside and the tire 'cold' from sitting overnight, you will put less air into that tire than you would if you had filled it at 68F. It is actually a complex issue as to how much air we should be putting in a tire but a good 'rule of thumb' is to add or subtract one PSI for each 10 degree change from 68F (I use 70 'cause I can do it in my head). So if it is 90F outside and I am shooting for 42 PSI, I put fill the tire to 44 PSI. If it is 20F out and you are the only motorcycle that will be out riding, and we are still shooting for the nominal 42 PSI, then I would fill the tire to 37 PSI.
The goal is basically to get the same amount of air in the tire at any ambient temperature.
Either that or just put air into the tire until the bottom is about the same shape as the top. :o
Brian
Isn't it just supposed to be 42 cold?? ???
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I have a digital roadgear gauge. I just put 42 psi cold no matter what the temp is and hit the road ;)
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Kind of.... the problem is what is 'cold'? I believe that the nominal cold is 20C or 68F. If you fill a tire to, say, 42 PSI when it is 90F outside and the tire 'cold' from sitting overnight, you will put less air into that tire than you would if you had filled it at 68F. It is actually a complex issue as to how much air we should be putting in a tire but a good 'rule of thumb' is to add or subtract one PSI for each 10 degree change from 68F (I use 70 'cause I can do it in my head). So if it is 90F outside and I am shooting for 42 PSI, I put fill the tire to 44 PSI. If it is 20F out and you are the only motorcycle that will be out riding, and we are still shooting for the nominal 42 PSI, then I would fill the tire to 37 PSI.
The goal is basically to get the same amount of air in the tire at any ambient temperature.
Either that or just put air into the tire until the bottom is about the same shape as the top. :o
Brian
Well lucky for me I live in the PNW, we haven't broke low 80's at all this year... :(
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I have a digital roadgear gauge. I just put 42 psi cold no matter what the temp is and hit the road ;)
+1 It ain't rocket science.
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Street tire pressure ratings are always cold. They only time when you would adjust pressures for hot tires (other than outside ambient air corrections) is when you are using race tires that are intended to be heat cycled - there is a significant difference between hot and cold temperatures and they are intentionally kept hot for grip.
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On my 09 the pressure goes up as i ride and if i run through a set of twisties the pressure goes up and then goes back down on a straight section ... according to the dash read out.
are you sayin that the computer compensates for the tire warming up?
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Of course the temperature will go up when you ride aggressively and down when you straighten out. I'm not sure why the TPS would adjust itself for temperature, other than for internal calibration.
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I usually run my Road Pilot 2's at abt 41 lbs. when the tires are warm according to the Tire Pressuse Sensors which by the way agree with my digital read out tire pressure guage. I find if I fill them to abt 39 lbs in the morning after a few miles of riding they come right up to abt 41 when the tires warm up and the bike seems to handle fine.
Fred
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Well lucky for me I live in the PNW, we haven't broke low 80's at all this year... :(
:o
I live in North Texas and today is the 31st day in a row over 100! Supposed to hit at least 108 later this week. Needless to say, I'm limiting my riding to before 10:00 am.
I put 42 in my tires "cold", but with the nightly temp only getting down to about 84, that's not exactly the correct way to describe it. My onboard sensors read about 2-3 psi lower than my gauges (quality digital).
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:o
I live in North Texas and today is the 31st day in a row over 100! Supposed to hit at least 108 later this week. Needless to say, I'm limiting my riding to before 10:00 am.
I put 42 in my tires "cold", but with the nightly temp only getting down to about 84, that's not exactly the correct way to describe it. My onboard sensors read about 2-3 psi lower than my gauges (quality digital).
This is a good example of what BDF was explaining. Since you are filling the tires at about 20F above the "cold standard", you would need to put approximately 44psi in the tires to have the same amount of air in the tire as 42psi at 65F (or 68F - I've seen both used as the stated "cold" temp).
Air expands as it is heated. More expansion = more psi. More air mass (volume? I regularly misuse the words) = more psi. The TPS in essence calculates the air mass by comparing psi & temp, and reports it as a compensated psi figure. If the air in the tires was perfectly dry and the display resolved 10ths of a psi, the display would be pretty constant. As with any electromechanical device, it is possible to have an inaccurate unit, but the tech is pretty accurate for the most part. The more moisture in the air in the tires, the more the pressure rise curve is affected as the tires warm up. IE, if your TPS moves a lot between hot and cold, you probably have a lot of moisture in your tires.
It may not be rocket science, but it is science & physics. A lot of riders seem to struggle with the concept. Since I have confirmed that my TPS matches my gauges at 65F, I set the pressure cold to target a 42 readout on the TPS.
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tire and oil threads are always epic (http://i80.photobucket.com/albums/j180/stevewfl/bigthumb.gif)
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42 cold front, 42 cold rear.
want to know what they are at various "operating" temps, pop on a set of chicken hawk racing warmers. but who cares????????????? 42 cold 42 cold for the street.
tire warmers:
(http://i80.photobucket.com/albums/j180/stevewfl/orangebike.jpg)
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Thanks for the replies, I always run 42 front & rear cold. I know that it changes when the tire temp goes up but the post I was talking was a good read and I just wanted to reread it, I guess no one has a copy of it.
Could of went all day with out hearing
It ain't rocket science.
Makes one think they asked a DUMB question >:(
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Does any other bike have front tire spec'd for 42 psi? Every other bike I have owned was spec's for 36 psi front or at least a few pounds lower than the rear spec. I don't run 42 front because I feel its wrong to run same psi front and rear. And I feel my results have been good as far as mileage and handling.
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It did not strike me as a dumb question. As to the comment about it not being rocket science, neither is rocket science if you choose to look at it in a simplistic manner. ‘Fire on the bottom make rocket go up’ is a true statement as long as one is not trying to actually design a rocket. The physics going on in the gasses inside a tire can be quite complex but of course it is not practical to do scientific studies and collect endless data to fill a vehicle’s tire. On the other side of the coin, just about all of us use some type of gauge to try to put some known 'amount' of air into our tires; this is science all by itself and proves that most people do care how ‘full’ their tires really are.
Whatever works for the owner of the bike works for me. ;) I find it easy enough to add or subtract a few pounds based on the outside, ambient temperature to at least get within reason of the correct tire pressure and posted the method I use in an earlier post. For those who choose not to do that, great. For those who do not believe it makes any difference, also great.
Brian
Thanks for the replies, I always run 42 front & rear cold. I know that it changes when the tire temp goes up but the post I was talking was a good read and I just wanted to reread it, I guess no one has a copy of it.
Could of went all day with out hearing
It ain't rocket science.
Makes one think they asked a DUMB question >:(
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Reminds me of this ;D ;D ;D
http://youtu.be/THNPmhBl-8I (http://youtu.be/THNPmhBl-8I)
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Reminds me of this ;D ;D ;D
:rotflmao: :rotflmao: :rotflmao: :goodpost:
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Thanks for the replies, I always run 42 front & rear cold. I know that it changes when the tire temp goes up but the post I was talking was a good read and I just wanted to reread it, I guess no one has a copy of it.
Could of went all day with out hearing
It ain't rocket science.
Makes one think they asked a DUMB question >:(
I did not say it was a DUMB question. You are the one that inferred that from the response. I could have said it's so easy a caveman could do it but I didn't. Put the gauge on, check the pressure, make an adjustment by adding or decreasing said pressure with either the air gauge, sharp pointy thing, or compressed air source. I don't worry about it again until the next ride or trip. I've been checking air in tires for well over 40 years and haven't worried about air temperature vs air pressure vs what's supposed to be in there vs what's not. I consistently get good mileage and performance with all my tires/vehicles without stressing about it.
Oh, I'm not a rocket scientist, but if i need one I can go across the street and get one. Cavemen are harder to find....
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I fill mine to 42 LBS after mounting them, and usually wear them out before they need adjustment.
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My kind of guy.... :thumbs:
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I fill mine to 42 LBS after mounting them, and usually wear them out before they need adjustment.
If I could get you sponsored by Michelin you would have enough money left over to buy Cap'n Bob the first non KiPass equipped C14. ;D
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Great method. Another thing that would work would to to guesstimate how much air the tire will lose over its lifespan and put in enough extra air to 'split the difference'. For example, think it will lose 20 PSI and you want the actual pressure to be 42 PSI? No problem, just fill the tire to 52 PSI initially and 1/2 way through the time you have it the pressure will be exactly 42 PSI. When it hits 32 PSI throw the tire away and start again.
Brian
I fill mine to 42 LBS after mounting them, and usually wear them out before they need adjustment.
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You see, Brian, you're just over thinking the whole thing. In your case, you could have checked the air pressures (42lbs) before your marathon trip, go to the West coast and back (assuming no punctures), and return without checking it again. I know I went to Reno and back (from the East coast) and only checked pressures once (when I left) and that was a 10 or 11 day trip. I broke it up a bit with civilized (no cavemen) hotel stays at night, unlike yourself where you wanted to do it in one fell swoop... :hail:
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I can tell you something funny about that very thing Jim, and it is absolutely true:
I rode to the other coast with my tires filled to about 42 PSI, and they read between 44 and 45 PSI for most of the trip. The tires were in great shape when I left but they showed a pretty nasty center flat from all that highway riding. When I got to the coast the tires were down maybe a lb. or so but they dropped another pound before I started back and I did not add any air on purpose to try to reduce the flatting of the rear tire. Got home with the on board sensors reading about 41 PSI and the rear tire looked a little better (more worn but also a bit closer to round).
Besides, I didn't want to mix any of that nasty west coast air in the east coast air in my tires.... :)
I have found my C-14 to be very sensitive to tire pressure as it relates to rear tire wear. Just a couple of PSI below the ideal pressure and the rear tires will wear badly just outside the hard center of a two- compound tire (Michelin and Pirelli that I have tried). A couple of pounds over and they wear badly directly in the center (flatting). Just a guess but the compounds used in sport- touring tires are probably on the soft side for such a heavy bike as the C-14, especially when the bike is even slightly loaded with gear, passenger, etc.
Brian
You see, Brian, you're just over thinking the whole thing. In your case, you could have checked the air pressures (42lbs) before your marathon trip, go to the West coast and back (assuming no punctures), and return without checking it again. I know I went to Reno and back (from the East coast) and only checked pressures once (when I left) and that was a 10 or 11 day trip. I broke it up a bit with civilized (no cavemen) hotel stays at night, unlike yourself where you wanted to do it in one fell swoop... :hail:
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I just put 42 in mine and fahgetabout until the next ride for the most part. But my 42 may not be your 42 due to gauge discrepancies in accuracy. I had a good flat spot on mine after the trip but it was basically straight riding, unfortunately. Only twisties were the the ramps :'( . All I keep in the tires is 42. I haven't much played with pressures.
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Air expands as it is heated. More expansion = more psi. More air mass (volume? I regularly misuse the words) = more psi. The TPS in essence calculates the air mass by comparing psi & temp, and reports it as a compensated psi figure. If the air in the tires was perfectly dry and the display resolved 10ths of a psi, the display would be pretty constant. As with any electromechanical device, it is possible to have an inaccurate unit, but the tech is pretty accurate for the most part. The more moisture in the air in the tires, the more the pressure rise curve is affected as the tires warm up. IE, if your TPS moves a lot between hot and cold, you probably have a lot of moisture in your tires.
Huh? Did I miss something? Is the wheel sensor measuring the temperature of air inside of the tire or is this a larger programming feature to factor in outside ambient temps? Next question is how and why would this be necessary when the sensor merely needs to measure and report the pressure that exists inside of the tire in real time?
As I said, I may have missed something.
As far as accurate guages go, I've had a good dial guage for twenty odd years and it disagrees with my on-board readout. I also have a cheesier dial guage that is about 3 psi off (low) at 40psi, but it agrees with my on-board so I just use that one. I go with 42-44 with all of this in mind.
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Huh? Did I miss something? Is the wheel sensor measuring the temperature of air inside of the tire or is this a larger programming feature to factor in outside ambient temps?
Not sure
Next question is how and why would this be necessary when the sensor merely needs to measure and report the pressure that exists inside of the tire in real time?
Exactly. That was my problem with the whole concept. Don't try to "help" me, which means I now don't know what it is doing. Just show me the actual damn pressure in the tire!!!!
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Right...I could care less about temp compensation. Show me the 'real' pressure.
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Temperature compensation is an industrial standard for electronic pressure transducers. It’s all about making the sensor read more accurately in the world it lives in…one of changing temperatures. Without this they would only read accurate at one temperature. I suspect it is the same with our sensors and I don’t think it’s about compensating for the temperature of the tire or the air in the tire.
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Has anyone mentioned differences in altitude and barometric pressure (the pressure OUTSIDE the tire)?
And nobody has even mentioned that the tire (being rubber) expands and increases in available volume as it heats up. Thermal expansion of rubber is about six times that of steel, so... ...
Wait a minute. Now it IS sounding like rocket science. :-X
Just make sure that a good guage shows 42 psi in each tire at the start of your ride, note the pressure shown by the TPS for future reference just in case a tire begins to go flat, and get out there and ride your a$$ off.
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Exactly. That was my problem with the whole concept. Don't try to "help" me, which means I now don't know what it is doing. Just show me the actual damn pressure in the tire!!!!
I suspect the reason they run compensation calculations is the same reason there are so many "driving assistance features" in new luxury cars now. It's not for the avid cyclist who knows what they are doing, it's for the least common denominator (idiots). I guarantee that there are a significant number of people out there who would fill their tires to the 41 psi cold, then when their tires warm up and the gauge starts reading higher they would freak out and stop for fear of bursting their tires and let air out. Then they can't figure out why it's low the next time they ride, or they leave it low because "it always seems to come back to where it's supposed to be after I ride for awhile."
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Exactly right in my opinion. If the TPS read "65 PSI" when the tire was warm, the first thing that everyone who wants the raw data displayed would want to know is the tire temperature. More data and then they would need a chart to see if the new pressure aligns properly with the new, elevated temperature. I think Infineon (the folks who make the sensor's controller) made a wise decision to display a compensated pressure, and I do not think any controller manufactuerer will be foolish enough to supply one that displays the raw data.
Back in the early days there were a lot of people who were quite concerned about 0.10 volt changes in the voltage display. I can just imagine the panic that would set in if the voltage was displayed in real- time, starting voltage depressions, charging spikes and all.
In the words of Jack Nicholson- 'You want the truth? You can't handle the truth'
;)
Brian
I suspect the reason they run compensation calculations is the same reason there are so many "driving assistance features" in new luxury cars now. It's not for the avid cyclist who knows what they are doing, it's for the least common denominator (idiots). I guarantee that there are a significant number of people out there who would fill their tires to the 41 psi cold, then when their tires warm up and the gauge starts reading higher they would freak out and stop for fear of bursting their tires and let air out. Then they can't figure out why it's low the next time they ride, or they leave it low because "it always seems to come back to where it's supposed to be after I ride for awhile."
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Temperature compensation is an industrial standard for electronic pressure transducers. It’s all about making the sensor read more accurately in the world it lives in…one of changing temperatures. Without this they would only read accurate at one temperature. I suspect it is the same with our sensors and I don’t think it’s about compensating for the temperature of the tire or the air in the tire.
I wondered about this. I couldn't believe that the display didn't show 1 psi difference regardless of ambient temperature or riding conditions.
Mark
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In the words of Jack Nicholson- 'You want the truth? You can't handle the truth'
;)
Brian
You're probably right...
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Interesting. All this talk about pressure and I have been noticing on the display that both tires seem to have lost pressure a little more each week since my last (first) service. When I took it from service two months ago, it said "41" or "42" on both.
Yesterday they were reading 38 while cold OR hot. Figured it was time to check/fill for the first time on the new bike. Got out my gauge and portable inflator... wouldn't you know.... unlike my last bikes, THIS bike has wheel orientations that deny access to the valve at certain places. And with my luck, BOTH wheels were like that, while it was on the cover stand, locked, and just starting to rain. I managed to get to the rear one. It is EXACTLY 42. Hmm. I had to abort before the front tire.
Very odd. My gauge is notoriously VERY accurate. Not sure what to think about the situation now.
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So in a really hot climate (like here in Texas), I guess I should be compensating for the temperature. When my gauge reads 42psi, the TPM says about 38psi ("cold" here now is about 85 degrees in the morning or 105 in the afternoon). I want the best gas mileage and the longest tire wear, but I don't want to over-inflate my tires. Should I trust the TPM or should I break out the thermometer and slide-rule and figure out what pressure I should be running?
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Slide rule? Do they even make batteries for those things anymore? :D
You cannot really use the on- board tire pressure system to measure tire pressure because it already is temperature compensated. Unless you allow the system to do the compensation and always set the tire pressure so it reads the desired number on the dash display. That would be difficult with the bike stopped though. You only need to compensate if using a non temperature compensated pressure gauge such as a manual, hand- held gauge.
Again, just a rule of thumb that we can all do in our heads: for every 10F or so above or below the 'normal' temp. (68F) add or subtract one PSI when the tire is cold (when the tire has been sitting overnight without the vehicle being used). So you go out to get the bike and the temp. is 100F..... that is about 30 degrees above the setting temperature (70F is really close to 68F and makes it easy- remember, this is a rule of thumb, not an exacting scientific calculation) and you want to fill the tires to 42 PSI.... just add three (3) PSI and fill them to 45 PSI. 'Gallagher, is it just that easy? Yes, it is just that easy!' (before he smashes the apples between the pie plates with the patented "Sledge-o-matic").
Of course we can always make it more complex. A very quick search turned up this jewel by Toyota: http://www.toyotapart.com/TIRE_INFLATION_PRESSURE_COMPENSATION_AND_ADJUSTMENT_T-SB-0345-08.pdf (http://www.toyotapart.com/TIRE_INFLATION_PRESSURE_COMPENSATION_AND_ADJUSTMENT_T-SB-0345-08.pdf)
That document reads like a US tax worksheet. If you follow those directions carefully enough, you may not end up with any pressure in the tire and a headache.
Now that this subject has gone on for three pages it is time to inject some really useful information:
'Rule of thumb' is often claimed to originate in old English law and states roughly that 'you cannot beat your wife with a stick bigger than the diameter of your thumb.' In actual fact that claimed origin is without foundation and almost certainly false, and the expression itself seems to melt into antiquity. Still, it is more interesting than reading about the best way to calculate the mass of air that should be inserted into a given tire based entirely on pressure and temperature measurements alone.
Brian
So in a really hot climate (like here in Texas), I guess I should be compensating for the temperature. When my gauge reads 42psi, the TPM says about 38psi ("cold" here now is about 85 degrees in the morning or 105 in the afternoon). I want the best gas mileage and the longest tire wear, but I don't want to over-inflate my tires. Should I trust the TPM or should I break out the thermometer and slide-rule and figure out what pressure I should be running?
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Thanks, Brian. Looks like I need to add 2 to 3 psi to my tires and forget about it. I like it when the answer is simple. :)
But now I need an accurate thermometer, too! >:(
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Thanks, Brian. Looks like I need to add 2 to 3 psi to my tires and forget about it. I like it when the answer is simple. :)
But now I need an accurate thermometer, too! >:(
Start a new thread on that one, please. ;)