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Discussion Starter · #1 · (Edited)
Most everyone knows that air expands when hot, and thus making the tire pressure increase a bit. But did you have any idea how much it increases? I was shocked to find out and I've been riding a long long time.

This info is from a new TPMS that I just installed on the bike. Your results may vary. I started with 33 pounds COLD front......and 36 pounds COLD rear, before I went for a ride on an 80 degree day...for about 15 miles. Moderate riding .. close to the speed limits .. no fast corners.....on asphalt streets. I verified the air pressure with a Motion Pro air pressure gauge before I rode. The TPMS showed the exact same pressure as the regular air pressure gauge.

Before I rode...the TPMS showed 33 front and 36 rear. When I got back from the ride...the TPMS showed 36 front,...and 40 rear. So I gained 3 pounds in the front and 4 pounds in the rear just on a casual ride. I'm pretty sure that on a Hooligan ride...it would be a pound higher in each tire.

Interesting huh? I never suspected the air pressure in the tires to increase that much. The new TPMS also registers tire TEMP. Haven't checked that yet. I'm almost afraid to find out how hot the tires get.
 

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I knew they increased as well. I check pressures constantly at the track.

With a higher initial tire pressure you'd gain less pressure. The higher initial pressure reduces contact patch and tire flex, and therefor heat.
I'm not saying change pressures; just that it happens, and here's why. I usually run my street pressure in the mid 30's as well, and I have no doubt the rear is near 40 when I'm strafing the mountain twisties.

What system do you have on there that gives you pressure and temperature?
 

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And that is why I fill my tires with Helium. Proper pressure, no pressure gain and lighter tires, front and rear. Chitty Chitty, Zoom Zoom.

Ride Safe.
 

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I have been running TPMS on my cars, trailers and bikes for about 5 years, I think they are great, when I have had a puncher I have been able to choose where and when I fixed it as I get a warning they are loosing air.

They are great for confidence too, you know when the bike feels a little different and the first thought is your tyres, with the TPMS it is just a quick glance to confirm all is good with the tyres.
 
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Discussion Starter · #5 ·
I knew they increased as well. I check pressures constantly at the track.

With a higher initial tire pressure you'd gain less pressure. The higher initial pressure reduces contact patch and tire flex, and therefor heat.
I'm not saying change pressures; just that it happens, and here's why. I usually run my street pressure in the mid 30's as well, and I have no doubt the rear is near 40 when I'm strafing the mountain twisties.

What system do you have on there that gives you pressure and temperature?
It's a TPMS.
 

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Discussion Starter · #6 ·
And that is why I fill my tires with Helium. Proper pressure, no pressure gain and lighter tires, front and rear. Chitty Chitty, Zoom Zoom.

Ride Safe.
How do you know there is NO pressure gain with the helium?
 
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Tire pressures are so important for proper tire performance that I have a hard time believing that there are lot of folks that just don't bother to check, or they don't know to check them and how important it is. An example that I see regularly is my track bike tires......Michelin Power ones on the front and rear. I start off in the morning before I go on track with the rear set at 22 psi cold The front is set at 30 psi cold. After a session on the track (20 minutes total) and then straight back to the paddock, a quick check reveals 26 to 27 psi on the rear and 34 to 35 on the front. I will usually leave the tires alone during the first three morning sessions and then at lunch time, the bike is parked under the pop up canopy, in the shade and allowed to cool to ambient air temperature. Then, right before going back out on the track, the tires are adjusted back to 22/30 cold psi again.
 

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I read somewhere that +10% front & +20% rear tire psi from cold > warm is a good rule of thumb.

So the front from 33 to 36 is good. Might need to bring down the rear to be in the 33>39 window.

I run 32/32 for normal riding. 30/27 at the track cold. If I remember well I end up in the 33-34 F&R after a session.
 

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Discussion Starter · #12 ·

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Discussion Starter · #13 ·

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Chill, I'm using danged old air from the Black Max in the Airtight Garage, ....OOPS....Tornado inbound...sirens on... moot point.

Ride Safe.
 

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Discussion Starter · #16 ·
But seriously, put helium in the front tire, it will make it easier to keep that front wheel up!
Yeah...so will a fat chick passenger. The fatter...the better,.... for wheelies.
 
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I like fat girls,

Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, what part of Inert gas are you having trouble with?

Not to coin on phase, 'Are we stuck on Stupid?".......

Ride Smooth!
 

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Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, Inert, what part of Inert gas are you having trouble with?

Not to coin on phase, 'Are we stuck on Stupid?".......
The definition of inert says nothing about thermal expansion/contraction or lack of it.
 
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