What are the widths?
Assuming they are either square or assymetric and you really have 40s on the back and 35s on the front then the rolling circumference difference front and rear is either 4% or 7%..the limit lies around 1.5% ish..in which case the DCS unit will have a melt down as your sizes are outside its parameters..
I had a not dissimilar thing when I intentionally provoked the car with all sorts of serious warnings (that dissappeared on re-start) with a 2.5% error based on an incorrect front tyre size..