I had a pair of Michelin PR4's fitted to my 2008 XB12XT a couple of weeks back. The fitter recommended that I run them at 36psi front and 36psi rear, as running the front any lower makes the tyre wear unevenly. With 36psi in the front tyre the bike follows the ridges etc in the road surface (but the tyres only have a couple of hundred miles on them so they may still be breaking in). I've been using the same tyre fitter for years and the pressures he has advised me have always been spot on, but I can't help thinking he's probably not seen many Buells?

Is anyone else running PR4s? If so what pressures are you using?

38 in the rear for me

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08 Specialized Langster

What about the front Pash?

Same as you...

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08 Specialized Langster

Thanks, I'll give that a go.

Last time I checked the Michelin website, they recommended 34/40 for the XT

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

That's me in the wrong then

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08 Specialized Langster

Nope, just checked again and it now says 36/38

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

They seem to change their mind from time to time, I had some notes a while back that said 2.3 bar (33.5psi) front, 2.5 bar (36psi) rear. But whatever, I'll try 38 in the rear and 36 in the front.

thanks

To properly calculate tyre pressure it should be stamped on the side wall, and also the wheel weight needs to be known.

If the tyre says 50psi max at 200kg (for sake of argument) and you've a bike which is 100kg at each wheel, then the tyre pressure should be 25psi (ratio of 50 (psi max) / 200 (axle weight max) * 100 (actual weight) )

If you want to know your exact weight at the wheel cheaply, buy 4 cheap bathroom scales. 2 for the front 2 for the rear, and put a bit of wood over them to spread the load. Zero the reading and put the bike upright on the scales (not on the side stand). If you want to be fancy, sit on the bike as well and have someone hold everything vertical. This will give the real world weights and obviously takes into account the riders weight too.

Take the information from the side wall and set tyre pressures accordingly. This works for any vehicle. It's a bug bear of mine when someone says tyres should be pressure 'x'. How many ply are the tyres? What's the load rating of the tyres?... The tyre manufacturers know their products, so take their advise as gospel, not the handbook for the bike which was correct for the OME tyres.

As a quick rule of thumb though and not going through the hassle of exact weights, 36 / 38 sounds pretty good.

Nice one Chris

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08 Specialized Langster

Next time you get the bike mot'd make a note of the axle weights when they check the brakes on the rollers

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.