Author Topic: Consistent Tire Filling-Finally  (Read 5271 times)

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Offline 4Bikes

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Consistent Tire Filling-Finally
« on: August 19, 2013, 11:45:21 am »
I think I finally found the solution for fast and consistent tire filling.  First off, knowing gauges can be wrong, I have 5 tire gauges, and three of the best ones and the TPS monitors on the C-14 are in agreement when the Temp is in the 70’s.

Before I started doing this new method, after filling, my TPS readings were all over the place. For the past two years, I had to fire up the air compressor, dig out the reading glasses, and try to read an analog gauge introducing error.  I’m sharing a solution that is quick and easy and produces the same results every time.

-Buy a portable auxiliary air tank.   I filled it once in March, and it continues to top off the tires months later.  It’s fast filling tires now, and you can do it anywhere.
-Buy a Stockton Digital Air Gauge.  I got mine from Cycle Gear.  The large numbers and backlighting requires no reading glasses or bright lighting.  Since the Gauge is digital, it reads in 1/10th increments, and I find that it is accurate.  It does require two hands to operate. 
http://www.cyclegear.com/CycleGear/Accessories/Tools/Tire-%26-Wheel-Tools/brand/STOCKTON-TOOL-COMPANY/Professional-Digital-Tire-Gauge/p/43191_59409

I don’t have right angle valves on my C-14, but find the standard air chucks in the photo work just fine.  Simply over fill the tire by a pound or two.  One hand holds the Air Gauge on the valve, and the second one hand controls the bleed valve.  Watch the digital gauge countdown to your desired PSI (I use 42 PSI) and release the bleed valve.

The results when rolling out are the same 42 PSI every time.  By the time the tires warm up, I see double 44’s on the tire display every time.  Trust me, that before I started doing method; my TPS readings were all over the place.

Yes I think my TPS monitoring is accurate.  Does anybody else have a better idea? 

Silver 2011 C-14 and 2019 Versys 1000 SE LT+.  Previous rides: KZ-400, KZ-750, KZ-1000.  Keep the rubber side down.  Ride Fast......Live Slow......

Offline Fred_Harmon_TX

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Re: Consistent Tire Filling-Finally
« Reply #1 on: August 19, 2013, 11:55:34 am »
If you put a descant snake on your air hose, you can greatly reduce the amount of moisture that gets into your tires.

The "set point" temperature that the TPMS sensors are calibrated to is 68 degrees. If you set your tires as close to this temperature as you can, you'll find the TPMS will better agree with your tire gage.

Use a good digital tire gage instead of a mechanical one.

My experience is similar to yours, and it has proven to me that the TPMS sensors are precise and report the actual tire pressure within about 1lb of accuracy.
« Last Edit: August 19, 2013, 11:59:07 am by Fred_Harmon_TX »
Fred H.


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Offline 4Bikes

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Re: Consistent Tire Filling-Finally
« Reply #2 on: August 19, 2013, 04:41:57 pm »
Thanks for the tips Fred.  It’s been a while since I filled the tires with temps in the 40’s and 50’s.  If I recall correctly, I needed to fill to around 43.5 to 44 PSI to get the TPS to read 42 PSI.  Is that the TPS compensation part, meaning a cold tire needs more pressure?  How would you compensate for the cold?
Silver 2011 C-14 and 2019 Versys 1000 SE LT+.  Previous rides: KZ-400, KZ-750, KZ-1000.  Keep the rubber side down.  Ride Fast......Live Slow......

Offline 4Bikes

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Re: Consistent Tire Filling-Finally
« Reply #3 on: August 21, 2013, 02:21:46 pm »

Edit: I fixed this per Fred's correction below.
I did some checking and it looks like the air pressure in the tire will drop approx. 1 PSI for every 10 degree drop in temp.  So assuming the TPS does a good job of compensating for temperature, you would need to over fill Under Fill the tire when it’s cold to get the desired reading on the TPS.  If the tires are hot, you would want to under fill Over Fill the tire.  See the chart below.
« Last Edit: August 22, 2013, 02:02:05 pm by 4Bikes »
Silver 2011 C-14 and 2019 Versys 1000 SE LT+.  Previous rides: KZ-400, KZ-750, KZ-1000.  Keep the rubber side down.  Ride Fast......Live Slow......

Offline br

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Re: Consistent Tire Filling-Finally
« Reply #4 on: August 22, 2013, 11:51:13 am »
I have heard that filling your tires with nitrogen will stabilize air pressure. Is this true? cheers bill.

Offline Fred_Harmon_TX

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Re: Consistent Tire Filling-Finally
« Reply #5 on: August 22, 2013, 12:07:59 pm »
I did some checking and it looks like the air pressure in the tire will drop approx. 1 PSI for every 10 degree drop in temp.  So assuming the TPS does a good job of compensating for temperature, you would need to over fill the tire when it’s cold to get the desired reading on the TPS.  If the tires are hot, you would want to under fill the tire.


Wrong. When the tires are colder than 68 degrees, you would DECREASE the pressure. So if it was 55 degrees in your garage when you filled them with the tires and wheels cold soaked, you would put in one less pound, and only fill them to 41 psi. Because as they heat up the air expands. When the tires heat up to 65 degrees, the pressure should increase about 1 psi to make them 42 psi at 65 degrees.

If the wheels and tires are hotter than 65 degrees, then you INCREASE the amount of pressure you put in. The general rule of thumb is 1 psi for every 10 degrees, though it will vary some because the internal volume of motorcycle wheels is less than a car tire that this rule is based on. Furthermore, the front tire has less volume than the rear, so it won't need as much. Maybe half a pound for every 10 degrees on the front.




And yes, nitrogen is much drier than normal air and doesn't expand as much when heated, so its pressure will remain more constant over a wider temperature range. This is one of its advantages. You can achieve close to the same thing by using a desiccant snake on your air hose when you fill your tires to remove moisture content from the air you put in them.

http://www.amazon.com/DeVilbiss-Desiccant-Snake-DS20-DEV-130502/dp/B000UZPPKA

« Last Edit: August 22, 2013, 12:12:11 pm by Fred_Harmon_TX »
Fred H.


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Offline 4Bikes

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Re: Consistent Tire Filling-Finally
« Reply #6 on: August 22, 2013, 02:15:42 pm »
Fred, thanks for the info, I corrected my earlier post.

The thread specs were not listed on the dryer hose.  Can I assume that it would be a ¼” NPT thread used on a common air chuck?

Silver 2011 C-14 and 2019 Versys 1000 SE LT+.  Previous rides: KZ-400, KZ-750, KZ-1000.  Keep the rubber side down.  Ride Fast......Live Slow......