Confused on tyre pressures

[r6paul]

Hi all, just wondering if any of you have an explaniation.

Just looking through some R6 articles, and under tyre pressures it suggests:

Rear - 28 psi track. 40 psi road
Front - 30 psi track. 36 psi road


Why is there such a big difference for track and road use?! Its nearly just under half the psi on the rear tyre.

What effect does it have on the handleing and how does it make it a better ride for the track?!



Paul

[Lateshift]

on the track you are riding the bike a lot harder and as such the air inside the tyre heats up more, and expands more, by running lower tyre pressures you give the air more room to expand when it gets hotter :)

also the lower PSI is designed to flatten the tyre more, that way when you are cornering you get more surface on the tarmac, if the tyre pressure was higher there would be less "give" in the tyre and as such you would be running on less rubber in the corners :)

Lastly the reason you have slightly more in the front on the track is because its the front tyre that is going to give all the feedback once you hit the corners, and needs to be slightly sharper than the rear, the rear you can compensate for with throttle, but the front needs to tell you whats happening :)

[Juvenilerider]

There you go then.

I thought it was because it made them softer, more surface area etc, didn't think about the heat etc

[Lateshift]

this is why you always check the tyre pressures before using the tyre ;)

no point in taking a reading from a tyre where the air is heated and expanded ;)

[r6paul]

lateshift the founder of all knowlege. Cheers.

So if you go out for a ride, on the road, but you are hitting the countryside esp for corners would you recommend track pressures or road pressures, or maybe somewhere in the middle?

[Lateshift]

With road tyres on UK roads, unless you have roads that allow you to give it some for miles and miles, you need to factor in that every time you slow down or stop the tyres start cooling, so they never get anywhere near the full running temperature that you would find on a track.

So with that in mind you can afford to run higher pressures to keep the tyre shape because they are never going to expand as they would on a track.


However, as far as tyre pressures go, and its always a big debate this, you never go with what the bike manufacturer says, always with what the tyre manufacturer suggests, and as long as you dont go over that then its fine for "normal" riding.

Now if you take into account that weight plays an important part in tyre pressure and tyre performance then its a case of trial and error, for me on the Mille if i run at 36 on the front it can feel razor sharp, if i drop 2 psi out of it then it can feel too soft under braking, so i settle for 35 and it feels fine.

Now that could change from tyre to tyre too so bear that in mind, as i said its trial and error ;)

[Juvenilerider]

Obviously don't take try and error to literally though, you don't wanna make any kind of error under braking :p