Quick question about tyre pressures.

[MementoMori]

Hi there,

I have a CBR929RR Fireblade and run pressures of 36 on the front and 42 on the back. After a few months, the back's usually lost about 2psi but the front's always down at around 20 and it obviously feels like ass to ride.

Just wondered why the front goes so low over... .say.... 2/3 months whereas the back is fine. It did it on the old tyres and it's doing it on the new ones too so I ruled out a slow puncture.

Is that about normal for bikes? Just not experienced this quirk (hopefully not a problematic one) before.

Thanks very much.

Steph.
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The tiger who came for a pint

[tatters]

Air naturaly leaks out from between the bead and the rim of the wheel as well as the rubber compound its self, having corrosion on wheel rim can make this alot worst l,ve had to use bead sealant (black rubber glue) to leaking rims in the past when tyres have gone flat in space of a few days.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

[The Shaggy D.A.]

I'd be more concerned about only checking tyre pressures every 2-3 months
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Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[tatters]

If its only going down over a few months l would not worry about it, my BMW is fitted with one of the earlyest tubeless spoke wheels and they leak down over about 1 month.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

[Rowey]

I'd say either get a new valve fitted or check for corrosion around the bead.

My girfriends vespa kept loosing pressure on the back wheel. Turned out water had been sitting in the bead and got between the paint and metal causing it to flake off and ruin the seal.

I quick wire brush to get off the loose paint and corrosion then some bead sealant.
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ZX6R C6F.
Never argue with an idiot. They'll only bring you down to their level, and beat you with experience.

[chris-red]

[MementoMori]

Thanks for the responses, this answers my question.

Cheers guys.
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The tiger who came for a pint

[ws4936]