Which Tire Pressure Gauge to Believe?

[Paddler]

I now have 5 tire pressure gauges, four of the pencil type, one Accutire.  Of the pencil type, one is a freebee from Discount, two are unmarked, and the last is a Milton.  I bought the Milton recently because when I googled accurate tire gauge and it tested well.  I put 38# of air in my front tire on my 1250RS according to the Milton, which the Accutire reported at 37.5#.  My bike said 35#.  I put 40# in the front and 46# in the rear, the bike measured 36.8# and 42.6#, precisely on spec.  All my pencil type and tha Accutire are within 1# of each other.  The bike is off more than 3#.  Who do you believe?

[Bernie]

At what ambient temperature did you measure the tire pressure with your gauges?

Your bike is programmed to measure the pressure and then to adjust the reading to 68 degree F. 

For example at 78 F, 42 psi will only be 40-41 psi on the BMW readout.

Don’t over inflate your tires, but rather adjust them to a actual cold pressure of 36psi front and 42 psi rear.

[Paddler]

So, that pretty much makes the tire pressure monitor useless unless you always ride in 68F weather.  Combine that with the fact that it doesn't display pressure when the tires are cold and the bike is stationary, why bother with it?

[Hosstage]

Like oil pressure and temperature gauges, it is a reference more than an actual accurate reading. It's there to let you know of an anomaly, generally low pressure, and most importantly a warning of imminent danger due to sudden loss of pressure.

When setting pressure, use your gauges, and note the pressure indicated by the tpms when setting off.

[Paddler]

Why don't they report the actual pressure as measured by a tire pressure gauge?  And why don't they send the reading when the bike is stationary?  I'm kind of compulsive about my tire pressures and having an out of spec reading bugs me.

[Hosstage]

I can't answer any of those questions for you, I can only tell you I've never had a vehicle with tpms so I don't have the anxiety about it that it seems to be causing you.

Hopefully someone chimes in with some info for you.

[Paddler]

My Expedition measures actual pressure.  The BMW will only be accurate at 68F while the bike is moving.  Not very helpful.

[Hosstage]

If nothing else, it will at least alert you to a sudden loss of pressure, or alert you if pressure starts dropping slowly due to a leak.

[nh1200c]

4 hours ago, Paddler said:

My Expedition measures actual pressure.  The BMW will only be accurate at 68F while the bike is moving.  Not very helpful.

The temperature and external pressure compensation is an advantage if you understand it. You might want to read the TPMS section in your manual to understand the system a bit better. (As a simple example, if you are riding in the mountains of Northern California, as I was a week ago with the ambient temperature over 90F - what would you expect your gauges to tell you about your tire pressure? The TPMS sensor will let you know whether you are ok, or need to add (or release) pressure.

Ride safe - 
Larry

[eisenwal]

4 hours ago, Hosstage said:

If nothing else, it will at least alert you to a sudden loss of pressure, or alert you if pressure starts dropping slowly due to a leak.

 This is the best use of the TPM readings on the bike. As long as whatever pressure is shown remains stable, you can ride with peace of mind. It used to bug me that when I filled the tires to a certain pressure the bike showed something else. A bit of OCD here, but I got over it.

[dirtrider]

9 hours ago, Paddler said:

Why don't they report the actual pressure as measured by a tire pressure gauge?  And why don't they send the reading when the bike is stationary?  I'm kind of compulsive about my tire pressures and having an out of spec reading bugs me.

Morning Paddler

 

Why don't they report the actual pressure as measured by a tire pressure gauge?-- As with most vehicles with a tire pressure monitoring system those systems also include a low tire pressure warning system.  Having a low pressure warning then it needs to know the tire pressure at the ambient temperature. So that is what the system reports.  Some uplevel vehicles do have a user settable choice to show actual or temperature-compensated on the dash (it still functions as temperature compensated for the low pressure warning part). I wish BMW would do something like this on the BMW motorcycles (rider choice).  But unless the rider is informed & pressure vs temperature knowledgeable then showing actual on the dash is just asking for a lot of complaints, concerns,  & much  rider confusion.

 

If BMW dash reading showed actual tire pressures (not temp compensated) then what do think most (uninformed) riders would do when the dash showed the tires at 6 or 7 psi too high when riding at high speed on the freeway on a warm day?   Yep, freak out & probably let some air out.

Or ride off on a very cold morning & see the tire pressures showing 4 or 5 psi too  low? (again probably freak out & return home) 

 

And why don't they send the reading when the bike is stationary?-- It does send readings with the motorcycle stationary, it just doesn't send any readings until the in-wheel tire pressure sensors wake up after sitting for a while, and that takes moving (spinning the wheel). If the sensors didn't go to sleep when the motorcycle was parked for the night then the sensor batteries would have a very short life.  (do you want to have to remove the tires & replace the expensive sensors WAY more often, or would you rather just have to ride the motorcycle a short distance before the sensors come on-line & start reading?)

I'm kind of compulsive about my tire pressures and having an out of spec reading bugs me.-- Actually, unless you check &  fill your tires at 68°f  (with tires also at 68°f) then your handheld  gauge is wrong. Typically not enough to matter but it is still wrong (right reading but showing incorrect pressure when corrected to 68°f).  No matter what you use, somehow you need to (well should anyhow) temperature-compensate to get the correct tire pressures. For most riding the (cold) tire temperature is not that far from 68°f to make much difference when using a hand held gauge & considering the broad BMW pressure specification allowance. 

 

I'm kind of compulsive about my tire pressures and having an out of spec reading bugs me.--  The BMW tire pressures shown in your riders manual are are based on the tires being at 68°f cold. The suggested tire pressures in your riders manual are broad enough to cover most (nominal) riding conditions. So if you use a hand held gauge & fill your tires cold  at 108°f  (tires at 108°f) that means they are actually 4 psi low (that 4psi low is still actually  barely within specs & an outlier but still safe to ride.  

 

Your dash TPS reading will reflect that 4psi low as it bases it's readings on 68°f (so in this case the BMW TPS system is actually more accurate than a hand held gauge.) 

 

When checking/using a handheld (non temperature compensated) gauge if you really want to be compulsive about your tire pressures then you need to figure the temperature offset then check/fill accordingly. You don't want to go too far off the rails using temperature compensation but 3psi  either side of nominal (BMW specified)  and 3 psi +/- based on ambient temperature/tire temperature  is a good rule of thumb. So you don't want to fill /check your tires at 8°f ambient  by lowering the tires 6psi (use the 3psi max offset rule here).

 

On the other hand you don't want to fill/check your tires pressures at 108°f then ride up into the mountains at 18°f as the tires would be 9 psi too low at 18°f cold ride-off. (again just use the 3psi max-offset rule)

 

[Bernie]

I think the TPMS units are a huge advance in technology. In the old days we had to stop every few miles and check our air pressure with a gauge. Then we used the manual bicycle pump to adjust the air pressure. It took all day to go 50 miles. I recommend you sell your BMW and purchase a more advanced motor cycle, like a Ural or a Royal Enfield. 

[Paddler]

I just didn't want to go around having to calculate the whole PV= nRT thing.

[dirtrider]

On 8/5/2023 at 10:47 AM, Paddler said:

I just didn't want to go around having to calculate the whole PV= nRT thing.

Morning  Paddler

 

Using the dash readout then no calculating is necessary as the TPMS has already done that for you. You just need to find out how close it is to actual at 68°f  (or at least between 60°f to 75°f). Then use that offset for actual. So if it reads 2°f  lower than actual at 68°f then just use that off-set to know what you actually have.

 

On the other side, if you are "a compulsive type person",  unless checking at 68°f  (or checking at around 60°f to 75°f) you ALWAYS need to calculate if using a handheld (non temp compensated) gauge.  Real easy to calculate (even a caveman can do it) just figure 1psi offset per 10°f of temperature change from 68°f nominal.

 

So if your tire is supposed to be 40 psi cold & the tire temperature is between 60°f to 75°f then just set to 40 psi. If the tire temperature is 10°f under 68°f  (ie 58°f) then set to 39psi.  If the tire temperature is 10°f over 68°f  (ie 78°f) then set to 41psi.  

 

If you are not that anal then just roll off slowly until you get dash readings then use that (or use the offset you have determined if the dash TPMS if off a little).

 

Personally, if I think of it,  (before riding off) I just thump my tires with a 2.5 foot 1/2 drive extension, if they both sound the same as they have the last 20 times I have thumped them then I ride away at my usual brisk pace & don't think about tires unless they do something unexpected. 

 

Personally I really like the newer vehicle TPMS systems as I can check the tire pressures on my wife's SUV from my cell phone.  

[Bernie]

One way to get the TPMS sensors to give you a readout before or without moving the bike is to purchase and use a Wake-up tool.

WIth it you can wake up your sensors and get a readout on your dashboard. I think they are around $10.00 on Amazon. 

[TSConver]

Another example of this.  My Ram 2500 has tire pressures of 80psi.  When I set them to that at 70 degrees first thing in the morning then hook up my toyhauler and start driving I can watch them climb to about 88 to 90 psi.  Should I stop and let air out?  No because they are at the correct pressure when you adjust for temperature.  I honestly wish my truck had the compensation like my bike.

[bimmers]

So how do you know how much to add or let out when on the road and tire temp is say 100F rear and 90Front. The ambient thermometer on bikes and cars are not an exact science either. Depending on where they are located they show maybe even flow from cooling air.....

I would rather be the stupid me and understand that I set my tires at the ambient temp(being "cold") even if it is say 80F in the garage. 

WHen riding they get warmer and pressure goes up from wha they were. If it would get colder they would be under less pressure but how about external air pressure change. You ride up in the mountains and at a given PSI in the tires they will behave differently at different elevations.......... 

So preference would be to understand the behavior of tires and the relations effecting them. AND of course when it actually makes a difference, if it really doesn't make a difference then roughly right is better than exactly wrong........

 

I have cheap after market temp sensors that I assume show the real pressure without corrections for elevation and barometric pressure as well as temperature. All I've done is check them against my regular analog gauge and stick gauge which both are roughly right:)

 

H

[Hati]

6 hours ago, bimmers said:

So how do you know how much to add or let out when on the road

 

You shouldn't add or let out mid-trip any air at all. Tyre pressure should be checked only on cold tyres (before the trip) and unless there is a reason to tinker with them, left right alone until the next time you start a ride. This is one of the reason  why the temp compensation exists, as it is corrected to 20C ambient (IIRC), so you know how it changes, if at all while hot.

[dirtrider]

14 hours ago, bimmers said:

So how do you know how much to add or let out when on the road and tire temp is say 100F rear and 90Front. The ambient thermometer on bikes and cars are not an exact science either. Depending on where they are located they show maybe even flow from cooling air.....

I would rather be the stupid me and understand that I set my tires at the ambient temp(being "cold") even if it is say 80F in the garage. 

WHen riding they get warmer and pressure goes up from wha they were. If it would get colder they would be under less pressure but how about external air pressure change. You ride up in the mountains and at a given PSI in the tires they will behave differently at different elevations.......... 

So preference would be to understand the behavior of tires and the relations effecting them. AND of course when it actually makes a difference, if it really doesn't make a difference then roughly right is better than exactly wrong........

 

I have cheap after market temp sensors that I assume show the real pressure without corrections for elevation and barometric pressure as well as temperature. All I've done is check them against my regular analog gauge and stick gauge which both are roughly right:)

 

H

Morning bimmers

 

Yes, you can make this complicated if that is your thing or just do as most do that is to, check/fill cold then ride as usual.

 

You are correct in that altitude does make a difference. Your aftermarket TPMS system (probably attaches to the valve stems externally) would read the same as a handheld PSI-G gauge. If a rider is real anal then they could buy a high dollar PSI-A (actual) gauge then figure their own atmospheric pressure (measured) off-set.  Maybe even carry a Kestrel to check it. 

 

Most factory TMPS sensors are mounted inside the tire's air chamber so do not account for atmospheric pressure changes. I haven't delt with the factory TPMS systems in a number of years now so am not sure if the newer systems are altitude compensated or not (the ones I delt with were basically calibrated to around sea level). 

 

Seeing as most newer factory TPMS systems are on the CAN they could have access to the vehicles fuel injection barometric sensor output ( but the ones I worked with did not use that info). I'm not sure if any of the current factory TPMS systems use the vehicle's barometric sensor?   No reason they couldn't use it.

 

In any case it typically isn't a big deal as the typical lower ambient temperatures at altitude do somewhat off-set the lower atmospheric pressure.

 

It usually doesn't make a lot of difference when going up in altitude as temp vs atmospheric pressure somewhat compensates. 

 

It's the other way around that can effect things, if you live at high altitude & fill maintain your tires at high altitude then you can (under the right conditions)  get a low tire warning when you come down to lower altitudes in cold weather. 

 

   

[Hosstage]

Way overthinking tire pressure. Set them in the morning, ride it. If you don't like the way it handles, adjust the pressure slightly the next morning, ride it.

Worry more about what type of oil to use.

[Rougarou]

24 minutes ago, Hosstage said:

Way overthinking tire pressure. Set them in the morning, ride it. If you don't like the way it handles, adjust the pressure slightly the next morning, ride it.

Worry more about what type of oil to use.

 

Set them when you change tires, check them at some point before your next tire change.

[TSConver]

It is simple to estimate the pressure changes by 2 psi for every 10 degrees change in temperature.  If the pressure is 42 at 68 degrees and it is 83 degrees ambient then your cold tire pressure should be 45 psi ((83-68)/10 = 1.5).  Like wise if it is 53 degrees out your cold tire pressure would be 39psi ((53-68)/10=-1.5).

 

You can also look at charts.

 

But it is pretty small amount at normal atmospheric conditions.  Unless you are road racing you will not likely ever notice the difference.

 

[TSConver]

13 hours ago, bimmers said:

So how do you know how much to add or let out when on the road and tire temp is say 100F rear and 90Front. The ambient thermometer on bikes and cars are not an exact science either. Depending on where they are located they show maybe even flow from cooling air.....

I would rather be the stupid me and understand that I set my tires at the ambient temp(being "cold") even if it is say 80F in the garage. 

WHen riding they get warmer and pressure goes up from wha they were. If it would get colder they would be under less pressure but how about external air pressure change. You ride up in the mountains and at a given PSI in the tires they will behave differently at different elevations.......... 

So preference would be to understand the behavior of tires and the relations effecting them. AND of course when it actually makes a difference, if it really doesn't make a difference then roughly right is better than exactly wrong........

 

I have cheap after market temp sensors that I assume show the real pressure without corrections for elevation and barometric pressure as well as temperature. All I've done is check them against my regular analog gauge and stick gauge which both are roughly right:)

 

H

 

 

Tire inflation numbers from mfg are actually calculated at 20 degrees Celsius (68 F) and seal level.  If you are set correctly for that then there is no need to adjust them as you change elevation or the temperature changes.

 

Pressure changes about 0.5 psi per 1000 ft of elevation so even at 10k feet the pressure is only different by 5 psi.  So even if you are at the top of mt evans, the highest paved road in NA at 14k ft the pressure will have only gone up 7psi.  Not enough to worry about unless you were driving at that elevation for an extended time and since you are going up and down I would not even bother changing.  If you live in Denver and are always 5k ft above sea level I would adjust my tires down 2.5psi when cold.  This would be fine for really any elevation then.

[Bernie]

Too much air pressure reduces tire life. Your contact patch is reduced, your tires will slip easier as you accelerate and because of the reduced contact patch you need more braking force. Also a reduced contact patch can be dangerous, causing easier slides and slippage of your tires. Something else to remember. 

[Hosstage]

Should I change tires from a softer compound when riding switchbacks in the mountains to a harder compound when I finally come off the mountain to ride the slab home 1000 miles?

Enquiring minds want to know.

[bimmers]

Stirring it all up when I agree with most of you. Set it in the morning and ride unless you feel something is wrong or you get a low pressure warning.

I do have the simple ones attached to the valve stem outside tire but measures same pressure as is inside the valve unless I am missing something.

I do notice on my car that the pressure does increase up to 5psi with increased temperature, don't measure temp on this car (old one did). Living at sea level with high temp (south FL) so tire temp can easily exceed 100F for rear tire, front somewhat less. I actually do not know where the temp sensor sits, it could measure valve temp or inside air temp which both could be same. Out of curiosity I will measure tire surface temp next time I go out with IR thermo and compare.

 

BUT let's not make this to something we need to worrry about. It just leads to unnecessary issues like all fuzz about drinking water all the time, I survived childhood drinking when I felt it was needed not like my grand kids being strapped to a water bottle even in class nowadays. I guess no water fountains around.............. I digress.

 

Happy riding

 

H

[bimmers]

Hoss,

take the ques from F1 and Cycle racing and see how they change between hard, medium and soft along each race........ just kidding but sure carry a few sets of tires with you all the time.........

 

 

[Hosstage]

I hesitate to even bring up using nitrogen to inflate tires rather than air...

[dirtrider]

15 hours ago, bimmers said:

Stirring it all up when I agree with most of you. Set it in the morning and ride unless you feel something is wrong or you get a low pressure warning.

I do have the simple ones attached to the valve stem outside tire but measures same pressure as is inside the valve unless I am missing something.

I do notice on my car that the pressure does increase up to 5psi with increased temperature, don't measure temp on this car (old one did). Living at sea level with high temp (south FL) so tire temp can easily exceed 100F for rear tire, front somewhat less. I actually do not know where the temp sensor sits, it could measure valve temp or inside air temp which both could be same. Out of curiosity I will measure tire surface temp next time I go out with IR thermo and compare.

 

BUT let's not make this to something we need to worrry about. It just leads to unnecessary issues like all fuzz about drinking water all the time, I survived childhood drinking when I felt it was needed not like my grand kids being strapped to a water bottle even in class nowadays. I guess no water fountains around.............. I digress.

 

Happy riding

 

H

Afternoon bimmers

 

 I do have the simple ones attached to the valve stem outside tire but measures same pressure as is inside the valve unless I am missing something.-- It does measure the pressure inside the tire but uses the external atmospheric pressure as reference. When you see 40 psi on the gauge or external sensor TPMs system  it is really 40 psi + atmospheric pressure (actual) but the gauge and the external sensor TPMS system removes the atmospheric pressure from the actual. (0 on a tire pressure gauge is really (about) 14.7 psi at sea level) 

 

The "inside the tire" TPMS sensors have no idea what the "outside the tire"  atmospheric pressure is so that value needs to be programmed into the system (that is typically sea level or 14.7 psi for most factory TPMS systems).
  

So at 5000 feet elevation your valve cap system would show (14.7  minus 12.27)   or 2.43 psi  more than the very same tire at sea level .

 

On the "in tire sensor" (factory) system  it would not know it was at 5000 feet elevation so it would still show the pressure corrected to sea level. 

 

So if the same 40 psi tire was set at 68°f at sea level it would show 40psi on the "in tire" TPMS system at 5000 feet elevation & your valve cap system  would show 40 psi plus 2.43 psi or 42.43 psi at 68°f at 5000 feet elevation.  

[Skywagon]

I use to crew for a Formula Ford guy in Ca in the SCCA. I had the task of checking tire pressure. We set it once for each set of tires with a conventional gauge. If the race stopped and the tires were hot, we didn’t check them. Once was enough. The rule of thumb was 10% increase in pressure due to race tire heat was considered normal. Only if the driver said the car was squirrelly did we even look

 

During riding season here I check my tires once a week. Almost never need adjustment. 
 

We might be over thinking this. 

[bimmers]

DR that sounds right, that the internal one has no reference to outside as it is separated from the valve itself. Anyway I check them when I leave and just react to obvious abnormalities  during ride.

After this thread I will look into the cars a little more. I have a MB and a newer BMW that also indicates what the pressure should be, now I wonder what the inputs for that are as it does change from time to time.

 

Always something for a retired engineer to think of........

 

H

[Rougarou]

I checked the tire pressure on the RT last month after I'd been gone a couple of months.  I checked the pressure on the GSA last week 'cause I changed the tires.  Neither will get checked again prolly for another month or two. 

 

Bikes get ridden damn near daily, tire pressures are a rarely checked item.

 

You's all are waaaaaayyyyy overthinking this stuff.

[Hosstage]

Waay overthinking.

[MikeB60]

6 hours ago, Hosstage said:

Should I change tires from a softer compound when riding switchbacks in the mountains to a harder compound when I finally come off the mountain to ride the slab home 1000 miles?

Enquiring minds want to know.

Absolutely 

[9Mary7]

14 hours ago, Skywagon said:

We might be over thinking this. 

Lil bit........

[dirtrider]

18 hours ago, Hosstage said:

Should I change tires from a softer compound when riding switchbacks in the mountains to a harder compound when I finally come off the mountain to ride the slab home 1000 miles?

Enquiring minds want to know.

Morning Hosstage

 

 A number of tire companies have already done that for you as they offer dual compound,  triple compound, or even progressive compound tires. Harder rubber in the center & softer as you lean the motorcycle into a turn or curve onto the outer bands. 

 

Personally I don't really like the multi-compound tires as I tend to get step wear right where the compound changes to softer rubber. 

[Hosstage]

2 minutes ago, dirtrider said:

Morning Hosstage

 

 A number of tire companies have already done that for you as they offer dual compound,  triple compound, or even progressive compound tires. Harder rubber in the center & softer as you lean the motorcycle into a turn or curve onto the outer bands. 

 

Personally I don't really like the multi-compound tires as I tend to get step wear right where the compound changes to softer rubber. 

I run dual compound tires on my HD, so quite familiar. They work ok for my application, but there is occasionally an awkward transition between compounds on curves. Would love to go with a little softer compound for carving curvy roads, but longevity trumps in my case. A lot of miles chewed on straight or mildly curved roads.

 

My post about changing tires was sarcasm, of course!

[dirtrider]

1 minute ago, Hosstage said:

I run dual compound tires on my HD, so quite familiar. They work ok for my application, but there is occasionally an awkward transition between compounds on curves. Would love to go with a little softer compound for carving curvy roads, but longevity trumps in my case. A lot of miles chewed on straight or mildly curved roads.

 

My post about changing tires was sarcasm, of course!

Morning  Hosstage

 

My post about changing tires was sarcasm, of course!-- Of course it was but it still deserved an answer. 

[Hosstage]

I appreciate that.

[Rougarou]

50 minutes ago, Hosstage said:

I run dual compound tires on my HD,

 

I use Rotella

[Paddler]

1 hour ago, Rougarou said:

 

I use Rotella

I splurged on Castrol for the 1250RS last time.  ~$9/qt plus tax.  Super Tech 3614 filter, though.

 

When I changed out the front tires on both bikes a couple of weeks ago, both Metzler Z8s, the centers were proud of the sides.  Must be different compunds.

 

I'll just check my tire pressures in the morning before rides.  On multi-day trips I may adjust each morning if the temperature or altitude are significantly different from the day before.

[Hosstage]

I have a few stories of tires, pressure, failures that only nerds would care about, but had a friend go off road on a curve, luckily not hurt, bike was rideable but totalled.

Looking at it when we got it home, I see the tires, check the air. Front, 17 pounds, rear 18 pounds. I said these should be at least 32 and 36, when's the last time you checked?

Last spring.

As in last year last spring?

Yes.

Well, that's why you went flying. Please check the tires on your new bike more often.

So one day we ride, he checks his tires when we park, starts letting air out.

What are you doing?

Bringing them back down to 36.

No! Just check in the morning and you're good to go. Don't adjust hot unless they're low.

Kids. You can lead them to water, but it's a struggle to teach them about bike maintenance.

[Steveyacht]

On 8/9/2023 at 10:59 AM, Rougarou said:

 

I use Rotella

I didn't know Rotella made tires.

[Bernie]

4 minutes ago, Steveyacht said:

I didn't know Rotella made tires.

It’s traditional around here, that if a subject becomes too heavy or complicated to add a oil comment.

You will understand, if you ever meet @Rougarou in person.

[bimmers]

Remember to change the headlight Oil its getting lost among all oils, just like headlight cooling fluid..................And on a half serious note all water cooled boxers now have a coolant, just thought of it, haven't checked mine but we are degressing so that's it have a nice weekend .

 

H

[Steveyacht]

23 hours ago, Bernie said:

It’s traditional around here, that if a subject becomes too heavy or complicated to add a oil comment.

You will understand, if you ever meet @Rougarou in person.

Oh, I get it, as I'm a long time member of a Norton Owners forum.  My comment was made with my tongue firmly planted in cheek.   :)

 

[wbw6cos]

.........and don't get anybody started on the accuracy of the onboard ambient temperature readouts.  

 

 

 

(your Fahrenheit may vary)

[Hosstage]

My oil pressure reads 32psi at speed, but my buddie's exact same bike says 34psi at the same speed. Why is my oil pressure low and do I need to tear my motor down to fix it? .......

[dirtrider]

27 minutes ago, Hosstage said:

My oil pressure reads 32psi at speed, but my buddie's exact same bike says 34psi at the same speed. Why is my oil pressure low and do I need to tear my motor down to fix it? .......

Morning  Hosstage

 

Were you using the very same gauge to test both motorcycles? If so then were booth motorcycles using the same oil with same amount of miles on them? Were both motorcycles at the same oil temperature? 

 

Even then there can be a number of reasons that it varies, like different bearing clearances, slightly different pressure regulator valve spring pressures, being that close to each other with only a slight variance between motorcycles then those are pretty darn close. 

 

To keep this thread on point it needs a link to tire pressures, so Unlike tire pressures, (fixed containment) oil pressure has a lot more variables than tire pressures as oil pressure is dynamic as the oil continually flows and is continually recirculated.     

[Hosstage]

Again, my sarcasm does not transfer well! I'm sorry to have wasted your time dr, I was just being a pain in the ass.

There is no difference between 32 and 34 psi on stock dash mounted gauge, I was just pointing out that those gauges are basically a reference, not to be used as accurate measurements.