[Ray]

hmm any tips for tire pressure..

example..

1. when track surface temperture is hot should we lower pressure or rise it..
2. how to tell whether the tire is in the right pressure by looking at the wear
of the tire..
3. the feeling of the bike when the pressure is too high or too low..
4. the difference when using different pressure for front and back..
5. etc..

think this we help learner like us better than giving suggestion on what pressure to use as all of us are using different tires at different weather temp.. i have been trying out many times but still couldn't tell which pressure is ideal..


thanks

[abtech]

Start here info

But read the entire thread, as there is conflicting info . . .

[Ray]

hey thanks.. seems to find lots of infor there..

[tnarinen]

Originally Posted by Ray

hey thanks.. seems to find lots of infor there..

+1 We had one very hot track day last summer and a lot of people were having problems with traction. One guy who races 125's suggested "add some air into tires" and things improved immediately. And this same info with a good explanation was available here all along. Thanks abtech

[Ray]

something to add in..

kind of diffcult to discribe.. my tires seems like getting "chunks" of rubber instead of the usual nice smooth roughness I see on other track user..

[Ray]

just realise something... will too high pressure in the rear when hot cause the tire to shear chunky pieces of rubber?

[sporky]

i always run 34/39 on the diablo corsas for street riding, during track sessions it goes 3-4 down depending from the temperatures. The tire wears nice and I achieve relative fast warming cause of my weight (100kgr + gear). About the weight issue, i read an article recently stating that the bigger the weight of the rider, the less the wear in the tire, due to the fact that forces to the ground tend to balance tire drifting

s..

[rawrider]

First let me state most of my experiance comes from Dunlop race DOT's. Secondly, I am by no means an expert on tires. These are just my opinions from my experience with Dunlops:

1. when track surface temperture is hot should we lower pressure or rise it..
(Raising the air pressure will stiffen up the carcass thereby creating less flex and therefore less heat. Conversely, lowering the pressure creates more flex in the carcass and produces more heat)

2. how to tell whether the tire is in the right pressure by looking at the wear
of the tire..
(You want to have a somewhat uniform wavy pattern accross the contact area. You DO NOT want to see a single chewed up strip along the contact area)

3. the feeling of the bike when the pressure is too high or too low..
(Hmm... Tires work with the suspension so the more air pressure you have the stiffer your suspension may feel)

4. the difference when using different pressure for front and back..
(Most of the time you will end up using different pressure for both)

5. etc..
(Cant answer this one )

[Cal-Sportbike]

To expound on what was mentioned above...

It IS OK to adjust tire pressure during the day, even with a tire hot. The important thing is that you don't want to try to keep re-adjusting to "target" pressure.

So for example, say you decide you want to run a set of tires at 30/30 and after a couple sessions you feel they are squirming a bit much. So you check them again and they are 34-36 psi when hot. Whatever....just so you have a baseline to work with at that time. If you want your sidewalls to have a little less flex, you can ADD a couple psi (2psi is a good starting point) to see how they do. So on a cold day we may start as low as 28 rear and 30 front but if the day heats up more than expected we may add a couple PSI, especially on really soft carcass tires like Metzeler RaceTec or Pirelli Supercorsas.

As mentioned above, your suspension setup is part of this equation and should never be ignored either, since at times people can misconstrue a feeling of squirm for what is really an issue with compression/rebound making the tire not staying planted as well across the surface.

Good advice above...and remember that this is far from an exact science. Get a baseline, keep some notes for yourself, it helps a lot.

[CBR Riding Fool]

I was told by the guys at Wheel 2 Wheel, The Pirelli race tire vendor at Willow Springs the target hot temp for supercorsas and dragon slicks is 33PSI as per the pirelli engineers.

[WetShrub]

Originally Posted by Ray

something to add in..

kind of diffcult to discribe.. my tires seems like getting "chunks" of rubber instead of the usual nice smooth roughness I see on other track user..

Does your tire look like this? This is an example of cold tearing. Your tire isn't heating evenly and the top layer of rubber is shearing away. This can have to do with many things including tire pressure and suspension settings. There is a track here in California that is notorious for it and many discussions have been made about it. Some people change their suspension to adjust and sometimes it works, other times they try a different pressure. There seems to be no set rule for what fixes the problem because conditions change all the time and so does the bike. So I would suggest running what the tire rep recommends for pressure and then adjust your suspension damping (rebound and compression) to see what might work for you. To get a bunch of info on this topic try here:

http://www.bayarearidersforum.com/forums/search.php?s=&action=showresults&searchid=1175282& sortby=lastpost&sortorder=descending

[luvtolean]

Yeah, and as trackho is arguing, I've worked with the fastest people in the AFM, and they still tear the **** out of the left side of the rear no matter what you do.

[WetShrub]

Yeah, it's just how turn 2 is at T-hill. Bumpy, fast, and long so you get a lot of heat on the left side. Hopefully with the resurfacing it will help to get rid of some of it. That's an expensive track to ride at with race tires.