Registered Forum User
Big Twin
Posts: 1,973
Join Date: Apr 2004
Location: West Sussex
Mood: Train comes and I know its destination
The bike's handbook assumes you have OEM tyres, and so gives the recommendation for that particular make and type.
Always start off with the pressures recommended by the tyre manufacturer for the type of tyre you have (always assuming that the tyre is suitable for your bike!!). You can then fiddle around the margins to find your optimal pressures.