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Retired Pipe Polisher C2H6O+
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Discussion Starter · #1 ·
Forget for the moment the complicated procedure for checking tire pressure rise from cold to hot to determine the best pressure to use. I assume most people just check and set their desired tire pressure cold as instructed in the owners manual and by the tire manufacturers.

Now here's the question. Does "cold" mean when you first get up in the morning and it's 75 degrees out? Or does it mean just before you go for your ride in the afternoon when it's 95 degrees out? :think:

If you ride in the morning, come home and take a nap then go out again in the afternoon, do you reset your pressures to the afternoon "cold" pressure? :think:

That 20 degrees difference would be about a 2 psi difference! :eek:

:D
 

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Premium Member
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Good question and most wouldn’t give it a second thought. When I commuted, I was living in south east Virginia. Summers are very hot in the day and there can be pretty large temp swings from morning to afternoon. Enough to change tire pressure that I could feel. I became very obsessive about it. I would check it in the morning, normally needed to add some. After sitting in the hot sun all day, I would check it again before leaving work, normally having to let some air out. Also, on the rain question, I felt this recently. Using the 10/20% method, I have mentioned that I can feel the tires warm. This is because they are at a lower pressure when cold that I had been used to until they warmed up. I got caught in a pretty heavy rain on a ride two weeks ago, the bike felt like I was riding on cold tires pretty quickly.

There is probably no real good answer here. Better to stick with what you set as a cold pressure (defined as the pressure before riding the bike and after it has been sitting in its environment long enough for the tires to be the same temp as that environment) and adjust riding if faced with rain or the like. Road temps and ambient temps are out of your control once you’re on the ride, I guess you just have to adjust or bring along a compressor and tire gage!

Edit. I'll add that the 10/20 thing is really to get to that point where the tires warm up enough to be grippy(est). I use that for when I'm riding back roads. The difference is notable. Tires heat more because of the added friction created by lower air pressure and the rubber become softer. Tires get as hard (pressure wise) as they would be if I started with a higher cold pressure, but the rubber is softer... I do not use this for highway riding, and I probably wouldn’t use it if I was on a touring type trip. I have gone on two longer highway drones since adopting the 10/20 thing and both times I have gone back to my higher cold pressures. The tires are hard enough to handle light, but the rubber isn’t as hot and therefore are probably less susceptible to cooling rain and normal temp swings throughout the day. That and they will wear better. The 10/20 thing DOES accelerate wear. I was getting 6K plus out of Pilot Powers and one set of the Pures. I don't think that will be the case with this set... They are wearing faster, but very even center to sides.
 

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Mr Leakered
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I only check temps (bike or cars) in the morning, in the garage. Just a weird habit. Whether it is 40deg in the winter or 60deg + in the summer doesn't bother me too much.

Have a good one.
 

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Premium Member
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+1 Tony, but I have noticed on really hot days in the mountains when I'm pushing it I can feel a difference in the handling. Drop a couple of pounds and the bike feels more planted. So there are times when you start off with a set temp and due to riding conditions will need to fine tune the pressure.
 

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Or just fill with Nitrogen and forget about cold or hot tire temp. Will stay constant no matter if it's the cold morning or hot afternoon.


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Retired Pipe Polisher C2H6O+
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Discussion Starter · #6 ·
Or just fill with Nitrogen and forget about cold or hot tire temp. Will stay constant no matter if it's the cold morning or hot afternoon.


Sent from my iPhone using MO Free
Is that true, or is the change in pressure just less.
 

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If your on the street and not the track the pressure difference will be so small you won't notice any changes. Race teams use Nitrogen because it's easier to measure tire pressure throughout races and pressure varies slightly depending how hot the tires actually get.


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Retired Pipe Polisher C2H6O+
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19,081 Posts
Discussion Starter · #8 ·
If your on the street and not the track the pressure difference will be so small you won't notice any changes. Race teams use Nitrogen because it's easier to measure tire pressure throughout races and pressure varies slightly depending how hot the tires actually get.


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I not sure but since air is mostly nitrogen I believe nitrogen still will change pressure at about the same rate air. About 1 psi for each change of 10 degf.
 

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Yeah air has about 70-75% Nitrogen but pure Nitrogen will make the difference. For street use is not that big of a deal and performance will probably not change, but you won't need to check tire pressure as often and the molecule is larger so it won't leak out when stored and drier( if you live somewhere with lots of humidity the inner rim won't rust).


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The difference is due to the moisture content. N2 has less water in it thus expands less when hot.
N2 has a bigger molecule so another benefit it don't leak out the rubber as quickly, but tires should ave a good inner linner made with crosslinked poly cord so it shouldn't leak but thats a whole nother thread and then some... Thankfully i don't work in that feild anymore 95% of my old customers are now closed or moved to China..
 

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We use nitrogen in aircraft tyres for that very reason, however we only check the tyre pressures in the morning when the aircraft is sat in the hanger! But then again that is more down to our procedures. Also the aircraft tyres can go near 100deg C once the brakes have been applied on landing. Probably not a good idea to go near metal rims.

John
 

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Premium Member
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SOOOO one should get an in line air filter air dryer type thingy to reduce the moisture in the air installed in the bike tire???
Seems like it wouldn't hurt... AND drain the water out of the air compressor often...
 

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I don't check my pressures everytime I ride, since it never sits that long in the summers. I just kick the tires to make sure they ain't flat.;)
 
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