What's "normal" Tyre pressure differences when col

[Val]

Installed tire pressure monitor.


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The pressure shown is the pressure when cold 36psi/42psi which is recomended one for MT09. After short ride yesterday I've noticed the pressure rises to 39 psi front and 49 psi rear tyre. Is that "normal"?

I mean I know there is a rule of thumb for cars you always measure tyre pressure when cold.

The question here is what is acceptable rise of pressure after a ride?
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Adrian Monk: Unless I'm wrong, which, you know, I'm not...
Yamaha Fazer FZS 600, MT09, XSR 900

[Northern Monkey]

Change in pressure is calculated using the equation pv = nrt

In your tyre volume, n and r remain constant, the pressure changes in the same ratio as the temperature (measured in kelvin)

If you’re ike tyres stated at 10c or 283k, then this pressure rise would be given bY a temperature of (283 / 42 x 49) -273 which is 58c

Sounds like you weren’t going very hard to have the tyre temps less than 60
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Fisty: after polishing the tank with the glistenng beads of sweat from my full hot scrotum, I filled the headrace bearings with 10cc of my manmilk

[kramdra]

www.google.com/search?q=Gay-Lussac's+law

A 25-40 degree temperature increase is quite possible after a long or fast ride. That is 10-20% total energy of the gas, and the same proportion pressure increase.

Bin the valve cap monitors, they hold the valve open, not good if they fail. In-wheel sort do not appear that expensive, and are very common on cars.

[bacon]

Tyre pressures are always set when cold. As a tyre warms up, the pressure will of course increase.

Generally 36F 42R is what manufacturers reccomend, as it's the safest option if you have to take a pillion, or add luggage etc.

However, if you get your bike setup properly, for solo use, they will set your tyre pressures in the region of 36F 36R.

I have my MT09 set at 36F/36R and it works well.

[Val]

thank you guys,

according to the formula posted apparently 1 psi increase for 10F is the norm. Means 7 psi increase is expected and if the temp was 50F in the morning (10C) 7 psi means 70F increase which will make the tyre 120F (48C). Seems fine to me.

Yes I do consider to change it for valve rim mounted sensors at some point.
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Adrian Monk: Unless I'm wrong, which, you know, I'm not...
Yamaha Fazer FZS 600, MT09, XSR 900

[G]

Yes - that's quite reasonable.
On track you'd expect a few PSI raise, but start at a good lot lower pressure (ie you're generally looking for around 26 hot in the rear these days.)

[grr666]

[johnsmith222]

I would just check and set tyre pressures when cold, check at a minimum monthly, and don't worry about it.

Not sure how I feel about those attached to the valve cap too.

[RhynoCZ]

[kramdra]

[G]

You do get motorcycle ones that stick on the rim inside the tyre.

I've got some valve cap ones for my van - after having a puncture from a stone that I'd like to have known about a bit sooner - I made a point of getting metal valve stems as there's a good bit of weight on them compared to a normal valve cap.

The ones that go to bluetooth won't be compatible with the ones that have their own display as far as I know.

[MCN]

My BMW K bike has TPMS.
I use the indicated pressure increase it to let me know when the tires are warm enough to engage Sport Mode.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Val]

[sickpup]

[kramdra]

As you are a tire fitter I thought you would know more about them.

[Polarbear]

[Val]