tyre pressure

im not sure if in the right section here sorry if im not. Iv got a trackday at donington on tuesday at just wondered what tyre pressure i should run on my sv 650.

I did a track day on my pointy few weeks back, first session out i started with normal pressures n then just began steadily lowering them until it felt right (when riding of course) So would lower them after each session until the bike was settled.
There would be no set pressures as it will depend on things like track temp, weather n how hard your pushing it.

Braders. Which tyres are you running?

As Carl is pointing out, it totally depends on make of tyres your using....

A little pre-emtive answer.

If you're running Sports touring tyres they won't be as prone to tearing as full track tyres but the answer is the same.

"The pressure you want is the one that gives best tyre temperature and hence performance"

This is what you don't want...



Classic cold tearing (high pressure tear *see vid below for definition). This tyre was too hard and so didn't reach its correct temerature. Dropping 3psi out of this tyre would squish it more building more temperature and getting it hotter. The cold tearing would go away.

Cold tearing (high pressure tear *see vid below for definition) is a curve towards the centre of the tyre with the outer edge at 45 degrees to the centre of the tyre.

The pressures you run are dictated by the apperance of the tyre. It will differ from day to day and even hour to hour as the ambient and track temperature changes.

That shouldn't be daunting. Just come in after the session and look at the tyres. if they look like this, let them down a little, one PSI at a time until this goes away. The photo above is severe cold tearing and so I suggested 3 psi straight away.

In some circumstances it is possible to get cold tearing on only one side of the tyre (usual) , both sides (less usual), cold tearing on one side and hot tearing on the other (very unusual). Dunlop D211 GP's and D209 GP's are especially prone to tyre tear and I'm yet to see more than three that have not suffered. Very difficult tyres to get right.

On Sports Touring tyres (storms etc) the tyre is less likely to cold tear (high pressure tear *see vid below for definition) but you still follow the same rules. Drop the tyre pressure until it gets to the right temerature for the tack and present conditions.

Here a Sports touring tyre from this forum that has cold tear ( high pressure tear *see vid below for definition)... The explanation... "Yesterday I ran 32/38 at anglesey"



from this thread..
http://forums.sv650.org/showthread.php?p=1597075

too hard and caused cold tearing.


Hot tear (low pressure tear *see vid below for definition) has a linear band of smooth tyre and tear marks that run parallel to the side of the tyre. they don't curve inwards towards the centre. This comes in when you've overdone it and have let too much out of the tyres. They will feel greasy. Its more difficult to achieve hot tear as you'll feel the greasyness and do something about it before they tear.

For sports touring tyres drop them to 33/33 cold and start from there but again it depends on the tyre. Once I know what you are running (and how hard you ride) I'll have a better idea of where to start for the time of year.

C

Here's a great vid on tyre wear and pressures.

In it the guy uses the exact *opposite* terminology of what we in the UK usually call it (or at least what I've learned to call it anyway) (very helpful) So his hot tear is what I've called cold tear and his cold tear is what i have called hot tear.

Its usually called cold tear because you need to get the tyre hotter to get rid of it (lower the pressure)
Its usually called hot tear because you need to get the tyre cooller to get rid of it (raise the pressure)

He is saying that Hot tear is too much tyre pressure and the tyre being too cold
He is saying cold tear is too little tyre pressure and the tyre being too hot

Confusing!? You betcha!

Its probably easier to use low pressure tear and high pressure tear instead. Then there's no confusion

Alrite Carl,

I may have to hijack this thread for a second as I need the same answer!! I am running a CBR600 at Cadwell on the 4th of Octoer and have a pair of Maxxis Sports arriving on Monday, any ideas as far as pressures???

In advance... Cheers Mate

Howdy

To be honest mate, juts what I've written above. I don't know anyone who's used Maxxis on the track. Ironically, even the Maxxis team in BSB use Pirellis

Start with 33/33 cold and check them after the first session as soon as you come in.

Reduce the pressure as you see how they're wearing. The idea would be to have them no more than the recommended pressures for the bike (cold) when hot.

C

[chris8886]

Originally Posted by Berlin

Howdy

To be honest mate, juts what I've written above. I don't know anyone who's used Maxxis on the track. Ironically, even the Maxxis team in BSB use Pirellis

Start with 33/33 cold and check them after the first session as soon as you come in.

Reduce the pressure as you see how they're wearing. The idea would be to have them no more than the recommended pressures for the bike (cold) when hot.

C

isn't that because it's a one tyre championship?

Yep.