K75S Radials tyre pressures

[aces59]

Hi. Having finally gotten round to sorting the front end out I now have radials front and rear (plus fork service and Yamaha blue spot calipers)  I set them up at 33/36psi to start with but interested to know what other people running radials are using? Current fashion appears to be - the  higher the better!
k75 wheel.jpg (74.17 kB . 768x576 - viewed 277 times)

[The Mighty Gryphon]

What tire sizes are you running?

Are you running stock rims? 

Are you riding off road?

Beyond the front brakes, what modifications have you done to the bike?

For stock sizes on stock rims on an uncafe'd bike, 38psi front, 40-42 rear work pretty well for me.

[aces59]

Hi. Front end - Bridgestone Battleaxe BT023F 120/70/17 on 3.5x17 rim
Rear end BT023R 160/60/ZR18 on 4.5x18 rim
RAM rear shock. Front forks std SHOWA with 10w oil
Normal On Road riding - Bike pretty much stock
Cheers
Steve

[The Mighty Gryphon]

My 16V K100RS uses those size tires.  Inflation label specifies 42psi front and rear.  Your bike is about 40 pounds lighter, so I would start with a little less air, maybe 36 front and 38 rear.  See how the bike handles and rides. 

I wouldn't obsess over tire pressures.  Unless you are on the race track, a couple pounds +/- from optimum probably can't be felt, especially if you are mostly using the bike for commuting and sporty rides on country roads.

Air pressure relates to contact patch, more pressure smaller patch.  A big contact patch is good on warm dry pavement, but in the wet a big contact patch increases the likelihood of hydroplaning, especially as the tire wears and the water channels get shallower.  The bigger the patch is, the more water needs to be moved to make contact with the pavement.