Tire Pressure went up?

[GytRDunKat]

So, I checked this morning before I left, and both tires were at about 38 PSI. On the ride home, it was driving "wierd", It didn't concern me too much, but enough to make me want to do some checking.

I checked when I got home, and they were both 45 PSI? what the heck. I let the pressure out, and took it out for a quick spin, and everything seems fine. Is it normal to have pressure rise that much from sitting all day? It was about 89ish and very humid if that makes any difference. Also, the bike was sort of in the sun... Some shade, not much. But, 7 PSI from sun exposure? Maybe my gauge is whack?

The wierd feeling was most prominant and really low speeds... Almost like something was binding the stearing, and it didn't want to turn, but not really. It's hard to explain in text

Ideas? Is that normal? wierd..

I can here the "Check your tire pressure" everytime you ride statements coming now.

EDIT: (typo)

[paradoxmd]

riding on your tires heats them up as does just sitting in the sun. the heat causes the pressure to go up. not normally an issue. and i've heard that most guages are whack. at least the ones the size of a pen or pencil and the ones you find at the air pumps and gas stations.

[Anonymous]

When you check first thing in the morning (before any riding), 38 on the rear is ok...a little high.

But 38 front is way to high! Get it down to 33-34 in the morning (before any riding)

And it going up during the day is perfectly normal....don't let any air out. When you ride your tires warm up (as they should) and psi increases...by quite a bit sometimes. It's prefectly fine.

As far as guages go, the digital ones are the most accurate. Les Schwab uses them exclusivley and verified them across all the digital guages (meaning, they used 3 different types of digital gauges in 3 different brands and the psi was almost exact.) The problem is finding one that will fit in the behind the rotors.

[Range]

I have told this to several people...inflating with compressed NITROGEN is the best thing for tires....pressure fluctuates substantially less then with normal air (which is about 78% N2 and 21% O2 with 1% other gases) Because compound gasses expand at varying rates, pressures build up faster and to higher and lower variables. Another benifit to using nitrogen is that it contains NO MOISTURE which can cause problems with the valve sealing.

Cant get Nitrogen?....Costco is our area uses it....and I just happen to have several cylinders of the stuff at my shop (used for pressurizing portable fire extinguishers)

[GytRDunKat]

Crap, I already let the pressure out. I'll recheck in the morning... thank goodness for air compressors.

I'll see if I can find Nitrogen tomorrow. No costco's around here

Again, thanks all for your help... Everyone so cool and willing to help!!

[paradoxmd]

Cant get Nitrogen?....Costco is our area uses it....and I just happen to have several cylinders of the stuff at my shop (used for pressurizing portable fire extinguishers)

or if you can't find it there, try an aircraft mechanic at an airport. nitrogen is used in commercial aircraft tires for the same reasons range described.

[trojanftbl52]

I think nitrogen is a little overkill, just set the pressures where they should be and you will have no problems.

[katman05]

I run my Conti's at 36 front and 41 rear, I also put on angled valve stems which makes checking tire pressure alot easier. I use a digital gauge which I find accurate since I've tested it with 3 other gauges.

[tzortn]

The main reason why your tire pressure went up was because you checked it after riding. As the tire rolls it expands and contracts. This causes internal friction which causes heat build up.

Range is correct in that using a dry gas helps reduce the fluctuations in the tire pressure. If you are using a typical home air compressor you can add a dryer to it to help get the air out of the line. Another good thing is to make sure that you drain the condensation from your tank. It helps prevent your tank from corroding and will help keep the air dry.

[prokart53]

Used in auto racing as well. Check local speed shops.

[J. Kidd]

I think on average, every 10 degrees in ambient air temperature corrulates to a 1 psi change in tire pressure. And, as others have said, riding will increase tire pressure due to heat build up from the tire expanding and contracting.

[The CyberPoet]

Altitude changes make radical differences -- I know my tires were way different at the gap (2000 feet) than at home (sea level). Temps also make a radical difference, which is why you are instructed by all the tire manufacturers to check your tires "cold" (i.e. - before you ever ride on them).

Depending on your body-weight & tire type, your pressures may be a bit high. I tend to run 36-37 front/38-39 rear on the Z6's, given a 215 lb rider plus full gear & lots of tools under the seat, and add another 1lb front & rear if I'm doing long highway cruising or carrying my saddlebags loaded up.

Cheers,
=-= The CyberPoet

[WildKat]

Altitude changes make radical differences -- I know my tires were way different at the gap (2000 feet) than at home (sea level). Temps also make a radical difference, which is why you are instructed by all the tire manufacturers to check your tires "cold" (i.e. - before you ever ride on them).

Depending on your body-weight & tire type, your pressures may be a bit high. I tend to run 36-37 front/38-39 rear on the Z6's, given a 215 lb rider plus full gear & lots of tools under the seat, and add another 1lb front & rear if I'm doing long highway cruising or carrying my saddlebags loaded up.

Cheers,
=-= The CyberPoet

Got that right..last year my pressure was at normal range.. bout 36 in the rear and 34 in the front before I left..then I got to the Fontana and both were right around 25 psi !

Same thing happened after I got home I had to let some air out because both were at 40+ when I got back from the climate and altitude changes. Now this year oddly enough even with all the rides up the skyway my pressure stayed pretty much on par.

[Mojoe]

The brand of tires makes a difference as well. running 38 in one brand may work great, but in another brand it might not. 38 was ideal with my metzeller on the rear, but the battlax I have on now sucks at 38 and I had to jack it up to 41. at 38 it felt "soft" and felt weird in the turns.

[steves]

The main reason why your tire pressure went up was because you checked it after riding. As the tire rolls it expands and contracts. This causes internal friction which causes heat build up.

Range is correct in that using a dry gas helps reduce the fluctuations in the tire pressure. If you are using a typical home air compressor you can add a dryer to it to help get the moisture out of the line. Another good thing is to make sure that you drain the condensation from your tank. It helps prevent your tank from corroding and will help keep the air dry.

How does one remove the air from the air line?