Wide road rims - pressure?

[nammynake]

Here's my current pressures for two wheelset/tyre combos:

(1) Normal width (Fulcrum Racing 5) with 23mm tyres = 95/105 PSI Front/Rear
(2) Normal width (Ksyrium) with 25 mm tyres = 80/90

These seems to suit my weight (63kg) and the types of road surface I ride on. The 23mm tyres could probably be dropped a tad but I'm nervous about pinch flats.

I've just bought some wide rims (17mm internal, 25mm brake track) to be used with 25mm tyres. I rode them today at 80/90 and they felt pretty harsh over rougher roads. Some of this could be the wheels themselves but it felt like the pressure was causing them to be a bit skittish over rougher roads. Is there a rule of thumb for pressures on wide rims and wide tyres? Seems like I need to go lower to get the comfort level right but would say 75/85 be too low and risk flats?

[Cagey]

These are the Assaults, yes?

Can't advise exactly what you should be running, but I have the same wheels and with 25mm GP4000s currently run 85/95. I'm 6' 2" and 76kg, and am finding these pressures fine for me. I probably could lose a few psi (and kg...), but I just dont particularly like the feel of 'squishy' tyres...

[nammynake]

Yes the new Assault SLG. Think I'll try dropping 5 PSI and take it from there. The tyres (Mavic Yksion) state MINIMUM pressure of 100 psi...not sure why!

[matt-ITR]

17mm internal is not what I would consider a wide rim.