Bottom line is, the VSS, as far as tire rotation goes, is very forgiving. I don't think you'll be able to fit tires that will give you a problem. What the VSS system is primarily looking for is sudden, and fairly drastic, changes in rotational speeds between wheels. Like one wheel quickly going much slower (locking up) or much faster (spinning) in relationship to the the other tires. It is not all that concerned with a continual and constant discrepancy between the front and rear wheels. Though I think that if you put 2 very different tire sizes on the front the VSS would cry 'Foul' pretty quickly. But who would do that?