| Thanks for the replies.
The following is taken from the pirelli web site:
"Tyre Pressure
It is important to always inflate the tyre to the correct pressure. Be sure to check cold inflation pressure frequently (i.e. once a week). Although most motorcyclists love to work on their bikes, they seldom remember to check tyre pressures. Correct tyre pressure, however, is critical for safe handling. Over-inflation or extreme tyre pressure will impair your riding comfort and decrease the contact of the tyre with the road. Under-inflation or too little air pressure will result in poor handling and the bike will be inclined to "wander." Improper and insufficient tyre pressure will also cause rapid tyre wear, an increase in fuel consumption, lower top speed, and provide less control. Remember to check the inflation pressure of your tyres weekly.
You will find the correct pressure in the operating manual of the motorcycle. The manufacturer's information is the minimum values only. With luggage or with a second rider the rear tyre needs an extra 0.2 bar, and for high speed riding the pressure of the front tyre should also be increased by 0.2 bar.
Attention: When the recommended pressure has been changed for use off-road (race track, off-road), it must be reset to the correct value before riding on the street."
The tyre fitment chart for the ST4S recommends 2.2 bar front, 2.5 bar rear for each type of tyre in the list presented.
I run with 2.5 & 2.9 due to the 2 up with luggage loading, rather thsn the 32/36 above, and that matchs the pressures in the bike manual.
Its interesting to see the same Pirelli tyres fitted to an 08 R1 (my other bike) are quoted as 2.5 & 2.9 for normal use. In fact Ducatis are the only bike I can see that gets quoted with a lower pressure...
Thanks again for the comments, I'll drop the pressures for at least the start of our next trip and see how we get on.
Cheers,
John.  | 
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