Apologies, didnt click that it was an 899 doh! That changes things a bit- the stock tires are 180's. The manual says;
"In the case of minor differences, such as tires of a
different make and/or model than the OE ones, but
with the same size (rear = 180/60ZR17; front =
120/70 ZR17), it may be sufficient to select the
suitable level setting from those available in order to
restore optimal system operation.
If tires of a different size class are used or if the tire
dimensions differ significantly from the original tires,
it may be that the system operation is affected to the
point where none of the 8 available level settings will
give satisfactory results. In this case is it is advisable
to deactivate the traction control system."
So no tire calibration adjustment on 190's, that does not mean TC wont function, but its not going to respond as predicted in the book.
I would have thought that spinning up in 4th is a more throttle control issue than suspension and tires given that you're on SC2's. Before doing anything, go up to TC 3 and see if that helps.