Tyre size & Tech II question

[iandonald]

My MY2000 9-3SE Coupe is supposed to have 195/60 R15 tyres, but had been fitted with brand new 215/60 R15 tyres and wheels off the 9-3SS Linear when I bought it. I noticed that the SID fuel consumption is always optimistic and also that mileage reads a little low compared with SWMBO's car for same journey (76 v 80 miles). I calculated that the tyre circumference may be 75mm greater than SID thinks? Any experts know whether a) this is right and B) can it be adjusted to be more accurate on both counts, and presumably mph? Thanks - Ian

[murphwiz]

the tyre size can be adjusted with tech2.

[markcanderson]

.. but only within the bounds of what was considered standard for the car..

So on 15'' - 195/60-15.
on 16'' - 205/50 - 16
on 17'' - 215/45 - 17

[iandonald]

Thanks MarkA - I think you've answered the question! If these are the only TechII choices, when you calculate the tyre circumference then 205/50/16 would be the nearest setting for accuracy on my 215/60/15 tyres - unless anyone knows different?! Thanks.