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Old 01-23-2013, 10:55 AM   #41
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Quote:
Originally Posted by clayp View Post
Saying that low tire pressures cause higher temps is incorrect. Using the same tire, at 28psi hot vs 36psi hot the 28psi tire will be lower in temperature driving in the same conditions.
1. Define hot
2. Except for the track, everything I've ever read about tire pressure says to check when cold.
3. Compare two of the same tires under the same conditions. The one with lower cold PSI setting will heat up faster.

Quote:
Disadvantages of Underinflation

An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle’s tires are underinflated by only 6 psi it could lead to tire failure. Additionally, the tire’s tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability. While 6 psi doesn’t seem excessively low, remember, it usually represents about 20% of the tire’s recommended pressure.
http://www.tirerack.com/tires/tirete...e.jsp?techid=1
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Old 01-23-2013, 11:00 AM   #42
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if low tire pressures cause enough flex to heat up the tire considerably, the tire pressures would then increase proportionally by the gas law, then there would be less flex which would lead to less heat, etc . Somehow this auto-regulation cycle doesn't pass the sniff test. Low pressures can lead to tire squirm and reduced traction, but its not from overheating and pushing the tire compound out of its ideal temps for traction. If anyone wants to test this they are welcome to borrow my pyrometer.

Last edited by clayp; 01-23-2013 at 11:02 AM.
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Old 01-23-2013, 11:16 AM   #43
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Quote:
Originally Posted by clayp View Post
if low tire pressures cause enough flex to heat up the tire considerably, the tire pressures would then increase proportionally by the gas law, then there would be less flex which would lead to less heat, etc . Somehow this auto-regulation cycle doesn't pass the sniff test. Low pressures can lead to tire squirm and reduced traction, but its not from overheating and pushing the tire compound out of its ideal temps for traction. If anyone wants to test this they are welcome to borrow my pyrometer.
So what do you do when your tires get too hot? Let some air out? No, you add air.
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Old 01-23-2013, 11:16 AM   #44
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Quote:
Originally Posted by Volfy View Post
The ideal gas law your quoted is correct. The application is not. The temp increase when you pump up the tire - even to max allowable - will not raise the tire temp enough for you to notice. You can plug the numbers into PV = nRT to see.

The real reason tires get warmer with less tire pressure has to do with the tire flexing more. If you take a chunk of tire rubber and bend it back and forth quickly, that piece will heat up.

For example, I had picked up a nail driving our SUV one day. By the time I noticed the tail end feeling squirrely, the TPMS came on, so I stopped to check, the nailed tire was nearly flat and HOT to the touch. And that day I had been driving local at no more than 50mph.
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Old 01-23-2013, 11:19 AM   #45
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Quote:
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dang i have 30 rear and 20 front
WtF?
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Old 01-23-2013, 11:22 AM   #46
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Quote:
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So what do you do when your tires get too hot? Let some air out? No, you add air.
are you serious?


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Old 01-23-2013, 11:33 AM   #47
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Quote:
Originally Posted by Bevo View Post
So what do you do when your tires get too hot? Let some air out? No, you add air.
Quote:
Originally Posted by clayp View Post
are you serious?


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Yes, but obviously I'm dumbass so why don't you ask another expert beside me or yourself.

Note: I hope you don't let air out of your tires when you think they're too hot
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Old 01-23-2013, 11:39 AM   #48
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this thread is full of WIN!!! street guys should always set your tire pressures at 11psi it's optimal for wheelie conditions while going 135mph in 1st gear
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Old 01-23-2013, 11:47 AM   #49
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Quote:
Tire Inflation

Always keep the motorcycle manufacturer's recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. On some motorcycles, the recommended front and rear tire pressures will be different. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well.

Riding on tires with too little air pressure is dangerous. The tires will build excessive heat. This can cause a sudden tire failure that could lead to serious personal injury or death.

Underinflation may also:

1.Damage the tire leading to tire failure
2.Adversely affect vehicle cornering
3.Reduce tire life
4.Increase fuel consumption
5.Fatigue cracking
Click on Tire Tips: Bridgestone Motorcycle Tires (link)
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Last edited by Bevo; 01-23-2013 at 11:52 AM.
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Old 01-23-2013, 06:16 PM   #50
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I can't remember what is actually happening when it overheats and I can't find anything on it.
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Old 01-23-2013, 07:28 PM   #51
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Quote:
Originally Posted by clayp View Post
if low tire pressures cause enough flex to heat up the tire considerably, the tire pressures would then increase proportionally by the gas law, then there would be less flex which would lead to less heat, etc . Somehow this auto-regulation cycle doesn't pass the sniff test. Low pressures can lead to tire squirm and reduced traction, but its not from overheating and pushing the tire compound out of its ideal temps for traction. If anyone wants to test this they are welcome to borrow my pyrometer.
If your tire pressure runs low and the tire heats up from flexing too much, it will not get hot enough to increase the pressure again. The tire will blow up when the tire overheats.

Not really sure where you are going with it.
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Old 01-24-2013, 06:04 AM   #52
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Quote:
Originally Posted by xtelevisionset View Post
I can't remember what is actually happening when it overheats and I can't find anything on it.
When they overheat they start losing grip and often chunks of tread start coming off
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Old 01-24-2013, 06:08 AM   #53
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Results of High Speed and Low Pressure

..
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Old 01-24-2013, 08:21 AM   #54
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well I read up some more on this and Bevo and Volfy are correct - low pressures lead to excess flex and flattening of the tire - on a motorcycle it is an issue vs a car which wants a flat contact patch - which increases rolling resistance, friction, and increased tread temperatures. The temps of the air in the tire may not increase as rapidly and the failure appears to be delamination of the actual tread/casing.

My thought was if the air in the tire increased in temps, you usually get an extra 1 psi per 10 deg F of temp increase, so a 25 psi tire at 70F would heat up another 70 degrees (total 140 F) then the pressure would rise 7psi to 32 psi which would seemingly help solve the underinflation. However rubber is a pretty good insulator and the tread temps would not raise the tire air temps as quickly.

So apologies to all for any confusion on my part.
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Old 01-24-2013, 08:21 AM   #55
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well I read up some more on this and Bevo and Volfy are correct - low pressures lead to excess flex and flattening of the tire - on a motorcycle it is an issue vs a car which wants a flat contact patch - which increases rolling resistance, friction, and increased tread temperatures. The temps of the air in the tire may not increase as rapidly and the failure appears to be delamination of the actual tread/casing.

My thought was if the air in the tire increased in temps, you usually get an extra 1 psi per 10 deg F of temp increase, so a 25 psi tire at 70F would heat up another 70 degrees (total 140 F) then the pressure would rise 7psi to 32 psi which would seemingly help solve the underinflation. However rubber is a pretty good insulator and the tread temps would not raise the tire air temps as quickly.

So apologies to all for any confusion on my part.
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Old 01-24-2013, 04:11 PM   #56
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Quote:
Originally Posted by Racerxxx View Post
WtF?
I didnt mean to, i filled it up to 25-28? but its been in my garage for a month or so :( but ima go fill it up to 30 and probably add a tiny bit more air in the rear.

so i'll be running like 30 f and 32 rear, good idea? I just mounted the new tires on my bike the bt015's but theyve been sitting in my garage for like 5 years lol but I mean once i rode around with the not so grippy surface underneath wasnt too bad, its actually got some grip but I'm looking to buy some new tires anyway.. I know theyre not as grippy as brand new tires, someone told me the performance was going to be absolutely non existent but I mean I've slowly pushed them and I've basically got it to where I have like no chicken stripes on the right side and just a little chicken strip on the left side and so far no sliding..
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Old 01-24-2013, 04:55 PM   #57
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shell gas station on west little york before queenston has a air pump that if you want all the air to come out your tire then head there psi dropped like 15psi after i was done using that piece of , maybe I thought it was user error but nope i tried it again so I could make it back home safely but it didnt work again it just released basically all my air. Also i think ima go buy a really nice air pressure checker from walmart because both of mine are giving me different readings..

so maybe I wasn't randomly running 20 f 30 r
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Old 01-24-2013, 04:57 PM   #58
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what should my pressure be on a 3.00-10-50 tire???

and its z rated
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Old 01-24-2013, 05:57 PM   #59
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Quote:
Originally Posted by Umayrkaleem View Post
shell gas station on west little york before queenston has a air pump that if you want all the air to come out your tire then head there psi dropped like 15psi after i was done using that piece of , maybe I thought it was user error but nope i tried it again so I could make it back home safely but it didnt work again it just released basically all my air. Also i think ima go buy a really nice air pressure checker from walmart because both of mine are giving me different readings..

so maybe I wasn't randomly running 20 f 30 r
While you're at Walmart by a bicycle floor pump to air up your tires. That's what I use when it's early in the morning and don't want to wake anyone up by firing up the air compressor.

Tire Temperature
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Old 01-24-2013, 06:13 PM   #60
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What is really important is to check your air pressure often, especially if you honk your horn a lot.

When you honk your horn, it removes air from your tires...I mean where else do you add air to your bike or car?

When I honk a lot, my handing gets all wonky.






























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