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Old 24-12-08, 02:03 PM   #31
Lozzo
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Default Re: Tyre pressure debate

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Originally Posted by Berlin View Post
Is the discussion in this tread is a bit bum about face?

Discussing cold tyre pressures is largely irrelevent when it's the hot pressure that matters, which is why racers use hot pressures to adjust their tyres.
I don't know one racer who sets his tyre pressures hot, and I don't know of any tyre companies who make race tyres who recommend you do.

In the past 4 years I've been in and around race paddocks and trackdays almost every other weekend - I see a lot of people checking tyre pressures and they always do them cold. The race bikes I prep and spanner are certainly only ever checked cold and the only time we change them is under extreme ambient temperature changes in the weather.
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Old 24-12-08, 03:38 PM   #32
Berlin
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Default Re: Tyre pressure debate

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Originally Posted by Lozzo View Post
I don't know one racer who sets his tyre pressures hot...
I do. quite a few of em, with the warmers on. I used to do it like this when I raced too. before every race. Maybe things have changed and maybe they know what they'll get once the warmers are on? I doubt your racer friends don't know what their hot pressures are even if they don't check them hot. I've watched race teams on the TV checking the pressures with the warmers on recently though.

C

Last edited by Berlin; 26-12-08 at 09:20 AM.
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Old 26-12-08, 09:13 AM   #33
Berlin
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Default Re: Tyre pressure debate

Hi Lozzo,
I found the following in June 2007's Bike magazines excellent article on Grip. (page 116 for those with the mag)

Direct quote.

Q: Does lowering my Tyre pressures give me more Grip? And should I only drop them for Trackdays?

A: It does. By extending the size of the contact patch. But you can go too low. In racing it's Hot pressures you want to check. But for the road we use cold pressures as an average guide. Many things affect the actual tyre temperature: your weight; The way you're riding; Speed; Ground temperature. The hotter a tyre, the greater the pressure. But go too low on cold pressures and the bike will become unstable.

Gary Hartshorne
Racing and technical manager, Bridgestone UK."


Its a great article if you can get your hands on the issue

Cheers,
Carl
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Old 26-12-08, 11:47 AM   #34
Lozzo
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Default Re: Tyre pressure debate

That's interesting. When we raced the Triumph 675 at Silverstone we had to run control tyres which were Michelin Pilot Race. We had no experience of them prior to going out in qualifying (He'd run Metzeler Racetechs in practice) and had no idea what pressures to run. I went and had a word with the Michelin guys on site and they gave me cold pressures, so we worked with those. Over the course of the weekend Danny neve complained about tyre pressures, desite their being quite a difference in ambient temperatures for all four sessins on the bike (2 qualifying, 2 races)

The only time I was given a hot pressure to work with was when we tried some new Dunlops to use on our old RGV250 based 'thing'. We faffed about trying to get them right but never succeeded as the hot pressure was never consistent. In desperation I searched out a Dunlop tyre tech and he told me not to bother with hot pressures but to check them cold and run the front at 31psi and the rear at some ridiculously low pressure like 22psi to start as their rear carcass had extremely flexible sidewalls that generated a lot of heat. From then on Danny never complained about tyres, and the times I rode it on trackdays it handled wonderfully
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