Hi all the spec for my 1997 600 Monster is 120/60 ZR17 on the front. I have been offered a 120/70 ZR17 at a really good price and I'm not sure if it will fit? I noticed that the 1997 900 Monster has 120/70 ZR17 as the specified tyre. Looking at the tyre size calculation the 120/70 has a radius about 11mm larger than the 60 profile. What is the general opinion on whether the 120/70 will fit OK without causing any clearance (or other!) problems? Thanks Jim
You may well find that going larger means you hit the mudguard. Unless you have lots of room in there, stick with stock.
I very much doubt that there is any difference in tyre to mudguard clearance between M600 and M900, pretty sure the mudguards etc. are the same. I'd definitely use the 70 profile as I do on both M900 and 916, as an aside 748 (same chassis/mudguard as 916) also used to come from Ducati with 60 profile but most owners fit a 70.
If you have a 60 fitted you may find it pushes a bit wide with a 70 as the profile is a bit flatter. Most I know who had 996 etc went 60 from 70, opposite to post above
I used to use a 70 on my 748, despite the book saying it should have a 60. Never noticed a difference and it didn’t hit the mudguard.
I noticed a difference when I went from a 70 profile to a 60 on my M750 many years ago. It seemed to turn in a bit better from memory but that could have just been because I went from something that had been on there for a while and wasn't very 'sporty' to a brand new set of Michelin Pilot Power Pures (?) !
70 profile is fine and provides better rim security when you encounter potholes, BUT as it is slightly taller, you'll need to raise the rear of the bike or drop the forks correspondingly to retain handling. You can do this most easily by adding preload or adjusting the linkage rod if that's fitted to your bike. I have 748SPS and experienced similar. The right way to do setup is with measurements in a nice facility, but if you don't have time or these luxuries, ride the bike around a short course with some turns in, wind the spring up a bit (you could watch what happens to the rear using a tape measure if you want), ride same course, keep going and note how much more willing the bike seems to want turn. You'll reach a point where you've gone too far so it feels like there's a hinge in the middle; back it off a bit to your satisfaction and enjoy.
Ride height will increase but only in the order of around 5 - 6mm, probably not alot more than replacing a worn tyre with a new one? Whilst it will have some affect, I doubt many would notice in normal road use? Also will affect speedo accuracy but again, it won't be by much and I doubt that M600 used a different speedo drive to a 900, equipped with larger tyre?
Increasing spring preload on shock only affects the point at which the spring starts to compress. It doesn’t change the ride height. Adjusting the link rod on a bike that has one will however affect ride height*. As said above, increased tyre height will have negligible affect on handling and speedo. *I may be wrong here as my brain has turned to mush over the last year or so! Edit: I have refreshed my memory by looking at a couple of my suspension guides and realise that I was talking utter bollocks. I must have been thinking of compression damping. I have left the above comment as a record of my stupidity.
Just how much ride height is changed depends on the application but generally speaking adjusting preload will change ride height on a logarithmic scale when incremented, e.g. - if totally wound off or out before an adjustment is made, then the first small adjustment might show an imperceptible change in ride height compared with the same amount of adjustment made when preload is almost at it's maximum.
