The stagger in general biases your front to rear grip. A larger delta in my experience takes away steering.

I will be be the first to admit I am no expert when it comes to mod. I used to race on a low bite track with stock and larger tires gave more grip. When I began running mod I figured I would need loads of grip, so I ran larger tires at first, like a 44/42 r/f. I was amazed, after taking advice to cut them smaller, that even on the low grip carpet I raced on the car worked better with smaller tires. Maybe a better answer is run them as large as possible without grip rolling. Some of this will also be determined by differing perceptions of low vs high grip as well as other factors like carpet type and bumpyness. FWIW I start with the sizes in my first post on green layouts when I go to a new track. Although remembering now at Worlds in FL I do think we ran like 42.7 rears and 41.5 fronts because grip was abysmal. So maybe a little bigger than I mentioned could work after all, or maybe I should just quit droning on...