Front tyre 120/70 vs 110/80?

[TheMechwarrior]

All,

I have the non-ABS version of the ST1100 and I just noticed the bike I purchased is running a 120/70 on the front instead of the recommended 110/80.
Can anyone tell me what the performance/handling difference might be between the 2?

Cheers,

Mech.

[Brock]

mine had 120/70s fitted on police version, then couldnt get them for love nor money, now have 110/80 and it works well. The main problem with tyres for the front, is to keep the rolling radius correct, as the speedo is driven from the front wheel. Change the radius (therefore the circumference) and the distance covered per turn will change affecting the accuracy of the speedo.

[saaz]

While I prefer a 110/80, most of the 120/70s I have run work just as well.  As Brock mentions, the speedo will read a touch higher.  Funnily enough I just replaced a 110/80 BT021 with a 110/80 PR2, and the speedo is more accurate with the PR2.  So there is even a variation in sizing within 110/80 tyres.  Different brands have different profiles, and sometimes whether it is a 110/80 or a 120/70 matters less.