following on with this - by upping the profile doesn't that increase the pressure on the sidewall, particularly under hard front braking?

the standard profile on the 87&88 is 110/80/17, by increasing to 120 what would you recommend for the sidewall profile? stay at 80 or increase?

 

120 / 70 /17 is pretty much the most generally available size.

Iwas kinda getting at that as opposed to the 120 / 60 / 17 option

 

I replaced the SC21 2.5J rim with the SC24 3.5J rim and added a Metzeler 120/60/17 tyre.

The 60 profile will alter the speedo but since I haven't changed the sprocket cover etc, and am going to try a digital speedo for a change it doesn't matter so much. Can calibrate the digital speedo to suit the tyre circumference.

The tyre on the 2.5J was a 120/70/17 and is 4 yrs old. It looked OK with 3-4mm of tread left, but when it was off the bike and depressed it showed some interesting secrets.
The 120 on the 2.5J overreaches the rim by approx 20mm each side - which is a hell of alot.

Pics tell the story; added a Dunlop pic of worst case scenario...

 

So do you think a 60 profile will cup/scallop any less ?

 

As in low fork oil/ incorrect tyre pressure/ mismatched tyres?

 

as in shorter height in profile ie flatter tire patch

It's interesting - the 120/70 I have on the smaller rim
does not overreach the rim by 20 mm each side - not even close