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Correct air pressure


PastorJay

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PastorJay

My 2015 rt air tire pressure reads 40/45 on the bike. My decent air pressure gauge reads about 5lbs under that 36/41. 
Which should I go by?
thanks for the help

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92Merc

The BMW dash reports the pressure, recalculated to 68 degrees ambient temp.  So if you bike/outside is something other 68 degrees F, it'll report different.  So technically, both are correct.

Personally, I go by my manual gauge and tested with cold tires.  Where you keep it will vary depending on your preferences.  Your 36/41 is in the general area where most keep it.

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dirtrider
4 hours ago, PastorJay said:

My 2015 rt air tire pressure reads 40/45 on the bike. My decent air pressure gauge reads about 5lbs under that 36/41. 
Which should I go by?
thanks for the help

 

Afternoon  PastorJay

 

Personally I would not go by either until you get a known accurate gauge on those tires. 

 

As 92Merc says the dash shown tire pressures are adjusted to a nominal 68°f, but you still have a 5 PSI delta between the dash reading & your handheld gauge. 

 

At about 1 PSI change  per 10°f  that would mean the tires are 50°f  different than 68°f. (are they?) 

 

In any case, you should use a known ACCURATE tire pressure gauge for tire pressure setting, or cold checking. Try to check & set them at as close to 68°-70°f as you can (or figure about 1 PSI gain for every 10° above that)

 

You might find a tire store that has a tire pressure calibration master gauge that they will let you check your gauge against. 

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Scott9999
49 minutes ago, dirtrider said:

You might find a tire store that has a tire pressure calibration master gauge that they will let you check your gauge against. 

Man, I wish I knew of a place locally with a master gauge.  You'd think that maybe a good auto parts store should have one of those as a service to customers, but I never knew such a thing existed, let alone had the presence of mind to ask about it.

 

Instead, I've got about five gauges in the garage, and just use the averages.   🤣🤣🤣🙄😨

 

My 2018 RT seems to sync to my best gauge within +/- 1 PSI, so I've never questioned the dash report.

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wbw6cos

A tire shop for big trucks.   Or a Penske Truck leasing (maintenance facility), or other heavy truck shop that is open to the public.  Just ask.

 

Everytime I walk into our Penske, I walk RIGHT by the calibration station.   I have been meaning to bring my truck tire gauge to check it.  Penske is contracted to perform the maintenance on our company equipment.

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Skywagon

I’m a bit anal about checking line.  Growing up ( laugh about it now), I looked, kicked it, and then whopped the tires with a metal bar. If it bounced back, good to go; if not add some air and kick it one more time. Of course back then that meant pull out the bicycle pump and start pumping

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With any pressure gage, the pressure you are seeking (say 40 psi) should be at the middle of the range of the gauge to be accurate. (ie. The maximum reading on the gauge should be around 80 psi.). If your gauge is over 5 years, Chuck it and get a new one. I tend to prefer the battery digital gauges now days. They are relatively cheap and accurate. Always remember to check your tires cold. The warmer the tire the higher the pressure reading. A warm tire will normally read @4 psi over a cold one. 

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Okay everyone that makes good sense now. I live in the state of confusion NY. Upstate, very close proximity to Lake Ontario always colder. So I have been checking my tires at 45-50 degrees. 
thanks for all the input and help. 

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14 hours ago, dirtrider said:

Afternoon  PastorJay

 

Personally I would not go by either until you get a known accurate gauge on those tires. 

 

As 92Merc says the dash shown tire pressures are adjusted to a nominal 68°f, but you still have a 5 PSI delta between the dash reading & your handheld gauge. 

 

At about 1 PSI change  per 10°f  that would mean the tires are 50°f  different than 68°f. (are they?) 

 

In any case, you should use a known ACCURATE tire pressure gauge for tire pressure setting, or cold checking. Try to check & set them at as close to 68°-70°f as you can (or figure about 1 PSI gain for every 10° above that)

 

You might find a tire store that has a tire pressure calibration master gauge that they will let you check your gauge against. 

Thank man, problem solved. I have been checking my tires at 45-50 degrees. 
appreciate the help. 

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16 hours ago, 92Merc said:

The BMW dash reports the pressure, recalculated to 68 degrees ambient temp.  So if you bike/outside is something other 68 degrees F, it'll report different.  So technically, both are correct.

Personally, I go by my manual gauge and tested with cold tires.  Where you keep it will vary depending on your preferences.  Your 36/41 is in the general area where most keep it.

Thanks Merc. Been checking my air pressure at 45-50 degrees. 
appreciate the help. 

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12 hours ago, Skywagon said:

I’m a bit anal about checking line.  Growing up ( laugh about it now), I looked, kicked it, and then whopped the tires with a metal bar. If it bounced back, good to go; if not add some air and kick it one more time. Of course back then that meant pull out the bicycle pump and start pumping

Mornings David

 

I still use that (metal rod) method as a pre-ride quick test. A couple of thumps tells me if I have enough air in the tires to ride the darn thing.  If I hear a sound I don't like when thumping THEN I put  pressure gauge on the tire but otherwise I typically only check tire pressures at seasonal temperature changes or at motorcycle service. 

 

The only bikes that I mess with more frequent  tire pressure checking is on my dirt bikes as I run some of those down in the 16-18 psi range when riding loose dirt/sand  so the thump rod always makes them sound low. 

 

 

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I have a really nice calibrated pressure gauge that mostly stays in the tool box these days as I use these inexpensive pressure gauges all the time.  At their price I keep one on/in each motorcycle/car I own.  I checked the 5 I bought against my known good gauge and they were +/- 1 PSI to my reference gauge.  Being a nerd about it I put a sharpie note for the variance on the backside body of each gauge.  Resolution to 1/2 PSI which is plenty good enough.

 

SLIME Digital Tire Gauge, 5 to 150 PSI - 33M133|20017 - Grainger

 

They are compact enough to fit well  between the disc and a valve stem on the center of rims.  Can easily be cycled to display PSI, Bar, and kPa.  I really like the back lit nipple & display if I am checking in poor light on the road.  You can buy them just about anywhere and on line for under $10, and even at full list price around $16 it is still a good value because they are pretty darn accurate.

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5 hours ago, Paul De said:

I have a really nice calibrated pressure gauge that mostly stays in the tool box these days as I use these inexpensive pressure gauges all the time.  At their price I keep one on/in each motorcycle/car I own.  I checked the 5 I bought against my known good gauge and they were +/- 1 PSI to my reference gauge.  Being a nerd about it I put a sharpie note for the variance on the backside body of each gauge.  Resolution to 1/2 PSI which is plenty good enough.

 

SLIME Digital Tire Gauge, 5 to 150 PSI - 33M133|20017 - Grainger

 

They are compact enough to fit well  between the disc and a valve stem on the center of rims.  Can easily be cycled to display PSI, Bar, and kPa.  I really like the back lit nipple & display if I am checking in poor light on the road.  You can buy them just about anywhere and on line for under $10, and even at full list price around $16 it is still a good value because they are pretty darn accurate.

Well, actually, $8.59 shipped from Amazon, not that I like buying from that monopoly. 😒👍

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Ya know, what surprises me (having wasted yet another hour of web browsing on the subject) is that there doesn't appear to be a air pressure fill gauge (i.e. attached to your compressor hose) that is simply "set and forget".  One would think that the technology exist to simply set the gauge at say, 42 psi, attach the hose to your tire, press the button, have the gauge allow it to overfill by perhaps 5 lbs, and then bleed down to 42 psi and either turn off, or have the hose pop itself off the tire nipple.   

 

Anyhow, after surveying a zillion gauges (after Randy's helpful hit on tossing a 3 year old gauge) trying to find the best bang for the buck, I'm ready to check all the new stuff, and just stick with my stick gauge.  I've got a cheap Harbor Freight fill gauge to mount on the compressor hose, which gets me within range (maybe +5 lbs), and then I bleed it to my exact setting with the stick gauge. 

 

I will pick up one of Paul's recommended slime gauges, just because I need to add another gauge to my existing set of four or five, as an accuracy baseline. 🤣

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14 minutes ago, Scott9999 said:

Ya know, what surprises me (having wasted yet another hour of web browsing on the subject) is that there doesn't appear to be a air pressure fill gauge (i.e. attached to your compressor hose) that is simply "set and forget".  One would think that the technology exist to simply set the gauge at say, 42 psi, attach the hose to your tire, press the button, have the gauge allow it to overfill by perhaps 5 lbs, and then bleed down to 42 psi and either turn off, or have the hose pop itself off the tire nipple.   

 

Anyhow, after surveying a zillion gauges (after Randy's helpful hit on tossing a 3 year old gauge) trying to find the best bang for the buck, I'm ready to check all the new stuff, and just stick with my stick gauge.  I've got a cheap Harbor Freight fill gauge to mount on the compressor hose, which gets me within range (maybe +5 lbs), and then I bleed it to my exact setting with the stick gauge. 

 

I will pick up one of Paul's recommended slime gauges, just because I need to add another gauge to my existing set of four or five, as an accuracy baseline. 🤣

Afternoon  Scott

 

Those small electronic gauges (assuming somewhat accurate) are a big help if you check your motorcycle air pressure frequently. 

 

Those old analog gauges with a hose on the gauge are handy to attach but they do hold a sizable amount of air so can let air out of a small internal capacity motorcycle tire with each checking (most let 1/4 pound or more out with each checking. My long-hose older (very accurate) analog gauge lets out about 1/2 pound of air from a front motorcycle tire with each usage. 

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This one doesn't release a measurable amount of air with every check, I've done 2 or 3 checks in a row just to be sure and the pressure stays consistent. If it does release a 1/4 pound of air with those checks, I can live with that. The air release button is nice too, over fill a bit, bump the button until I get to my preferred pressure.

Has a tire tread depth gauge too.

 

IMG_20220513_155946157_HDR.thumb.jpg.c6a9698315c435f0a114fd7caad7a2c4.jpg

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25 minutes ago, Scott9999 said:

Ya know, what surprises me (having wasted yet another hour of web browsing on the subject) is that there doesn't appear to be a air pressure fill gauge (i.e. attached to your compressor hose) that is simply "set and forget".  One would think that the technology exist to simply set the gauge at say, 42 psi, attach the hose to your tire, press the button, have the gauge allow it to overfill by perhaps 5 lbs, and then bleed down to 42 psi and either turn off, or have the hose pop itself off the tire nipple.   

 

Anyhow, after surveying a zillion gauges (after Randy's helpful hit on tossing a 3 year old gauge) trying to find the best bang for the buck, I'm ready to check all the new stuff, and just stick with my stick gauge.  I've got a cheap Harbor Freight fill gauge to mount on the compressor hose, which gets me within range (maybe +5 lbs), and then I bleed it to my exact setting with the stick gauge. 

 

I will pick up one of Paul's recommended slime gauges, just because I need to add another gauge to my existing set of four or five, as an accuracy baseline. 🤣

 

I bought a dewalt tire inflator that has a gauge on it, as well as the ability to set a particular pressure and press a button.  It works pretty well too, the only issue is that because the connection is a screw on, you lose a certain amount of pressure during that unscrewing process.   It works very well on the RT because the valves are easy to access, etc... so I set the desired pressure to 0.5 psi high and about that little bit is lost.  On my RNineT with spoked wheels, its much harder.  I end up having to go a few psi high and then after doing the finger gymnastics to unscrew it I then use the gauge with a bleed down valve on the side to set the pressure to the correct value.

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1 hour ago, Hosstage said:

This one doesn't release a measurable amount of air with every check, I've done 2 or 3 checks in a row just to be sure and the pressure stays consistent. If it does release a 1/4 pound of air with those checks, I can live with that. The air release button is nice too, over fill a bit, bump the button until I get to my preferred pressure.

Has a tire tread depth gauge too.

 

IMG_20220513_155946157_HDR.thumb.jpg.c6a9698315c435f0a114fd7caad7a2c4.jpg

I have this same gauge. Not cheap but seems to be my most consistent of the four gauges I have.

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sleddriverSF

This unit is surprisingly accurate when filling up tires.  You spin the nob with the readout to the pressure you want, press the button and you can set it down and walk away.  It fills to your desired pressure and then shuts off.  I already have a bunch of Ridgid tools and it was on sale when I got it for like $39 so I thought it was worth that.

 

https://www.homedepot.com/p/RIDGID-18V-Cordless-Digital-Inflator-Tool-Only-R87044/313257505

 

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