Tire pressure question

krapzed · August 6th, 2014, 09:57 AM

Ok, so 1st, I did use 'Search', and 2nd this might sound like a stupid question, but since I do not know the answer, I'll ask it anyway...

I am aware that tire pressure should be checked/measured whilst the tire is cold.. BUT, should you measure while it is standing up in the stands (rear/front/whatever) or while both tires rest on the ground?

Alex · August 6th, 2014, 10:04 AM

Doesn't matter; the readings will be the same.

NevadaWolf · August 6th, 2014, 10:04 AM

As far as I am aware, weight on the tire (as in, on the ground) will not affect the amount of pressure inside the tire. Its only whether the air is hot or cold that is expands or contracts, giving different readings.

I check mine in both positions, depending on what I am doing at the time. Preflight walk around, on the ground. During regular chain inspection, up on a stand. Never noticed a difference.

If I am wrong and there is a recommended way, I am curious and would like to understand the reason.

shereth · August 6th, 2014, 10:16 AM

In theory, the weight of a load on a tire will cause a certain amount of deformation of said tire, reducing the volume of the tire and therefore increasing the pressure (Boyle's Law).

In practice, a tire is inflated to such a pressure that it resists deformation even under load. This, combined with the relatively low weight of a motorcycle means that the deformation of your tire, and therefore the increase in the internal pressure of the tire, is small enough to be negligible and essentially unmeasurable with your typical pressure gauge. You shouldn't see a difference one way or another.

NevadaWolf · August 6th, 2014, 10:35 AM

I stand corrected. Thank you @shereth.

ninjakuma · August 6th, 2014, 11:00 AM

August 6th, 2014, 09:57 AM	#1
krapzed ninjette.org member Name: Park Location: CT, USA Join Date: Jul 2013 Motorcycle(s): 2005 Ninja ZX6R / 2010 Ninja 250r (SOLD) Posts: 69	Tire pressure question Ok, so 1st, I did use 'Search', and 2nd this might sound like a stupid question, but since I do not know the answer, I'll ask it anyway... I am aware that tire pressure should be checked/measured whilst the tire is cold.. BUT, should you measure while it is standing up in the stands (rear/front/whatever) or while both tires rest on the ground?

August 6th, 2014, 10:04 AM	#2
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	Doesn't matter; the readings will be the same. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

August 6th, 2014, 10:04 AM	#3
NevadaWolf Certified looney toon Name: Teri Location: 39°52'40.7"N 118°23'53.8"W (Northern NV) Join Date: Jun 2012 Motorcycle(s): 2012 Ninja 250, 102k+ miles -- 2014 CB500X, 42k+ miles Posts: A lot. Blog Entries: 16 MOTM Jul '13, Jul '14	As far as I am aware, weight on the tire (as in, on the ground) will not affect the amount of pressure inside the tire. Its only whether the air is hot or cold that is expands or contracts, giving different readings. I check mine in both positions, depending on what I am doing at the time. Preflight walk around, on the ground. During regular chain inspection, up on a stand. Never noticed a difference. If I am wrong and there is a recommended way, I am curious and would like to understand the reason. __________________________________________________ <-- Linky Hey Unregistered! The code [you] shows the username currently logged in. IBA # 56020 AMA # 521481 Fun Rides! ][ My Videos ][ My Gear Hold yourself to the same rules you expect others to follow.

August 6th, 2014, 10:16 AM	#4
shereth ninjette.org member Name: Alan Location: Phoenix Join Date: Jan 2014 Motorcycle(s): 2012 Kawasaki Ninja 250 Posts: 73	In theory, the weight of a load on a tire will cause a certain amount of deformation of said tire, reducing the volume of the tire and therefore increasing the pressure (Boyle's Law). In practice, a tire is inflated to such a pressure that it resists deformation even under load. This, combined with the relatively low weight of a motorcycle means that the deformation of your tire, and therefore the increase in the internal pressure of the tire, is small enough to be negligible and essentially unmeasurable with your typical pressure gauge. You shouldn't see a difference one way or another.
	2 out of 2 members found this post helpful.

August 6th, 2014, 10:35 AM	#5
NevadaWolf Certified looney toon Name: Teri Location: 39°52'40.7"N 118°23'53.8"W (Northern NV) Join Date: Jun 2012 Motorcycle(s): 2012 Ninja 250, 102k+ miles -- 2014 CB500X, 42k+ miles Posts: A lot. Blog Entries: 16 MOTM Jul '13, Jul '14	I stand corrected. Thank you @shereth. __________________________________________________ <-- Linky Hey Unregistered! The code [you] shows the username currently logged in. IBA # 56020 AMA # 521481 Fun Rides! ][ My Videos ][ My Gear Hold yourself to the same rules you expect others to follow.

August 6th, 2014, 11:00 AM	#6
ninjakuma Stunts Extraodinar Name: Ninjakuma Location: Los Angeles Join Date: Jun 2014 Motorcycle(s): 1999 Ninja 250 Posts: 74	__________________________________________________ Will backflip for tips

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