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Michelin PR4 Pressures
https://ukbeg.com/forum/viewtopic.php?f=7&t=20519
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Author:  bones [ 14 Jul 2015 20:16 ]
Post subject:  Michelin PR4 Pressures

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?

Author:  pash [ 14 Jul 2015 20:37 ]
Post subject:  Re: Michelin PR4 Pressures

38 in the rear for me

Author:  bones [ 14 Jul 2015 20:39 ]
Post subject:  Re: Michelin PR4 Pressures

pash wrote:
38 in the rear for me


What about the front Pash?

Author:  pash [ 14 Jul 2015 20:43 ]
Post subject:  Re: Michelin PR4 Pressures

Same as you...

Author:  bones [ 14 Jul 2015 21:04 ]
Post subject:  Re: Michelin PR4 Pressures

pash wrote:
Same as you...


Thanks, I'll give that a go.

Author:  Maz [ 14 Jul 2015 22:25 ]
Post subject:  Re: Michelin PR4 Pressures

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

Author:  pash [ 14 Jul 2015 23:20 ]
Post subject:  Re: Michelin PR4 Pressures

That's me in the wrong then :x

Author:  Maz [ 15 Jul 2015 00:00 ]
Post subject:  Re: Michelin PR4 Pressures

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

Author:  bones [ 15 Jul 2015 13:45 ]
Post subject:  Re: Michelin PR4 Pressures

Maz wrote:
Nope, just checked again and it now says 36/38 :?


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

Author:  ulyChris [ 15 Jul 2015 15:49 ]
Post subject:  Re: Michelin PR4 Pressures

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.

Author:  pash [ 15 Jul 2015 16:40 ]
Post subject:  Re: Michelin PR4 Pressures

Nice one Chris

Author:  kevmean [ 16 Jul 2015 05:11 ]
Post subject:  Re: Michelin PR4 Pressures

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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