If all 4 tires duro 50, and I change the LF to a 42, what would the effect be on a dirt oval with no banking. Let’s just assume the kart is handling pretty good on pinks and blues.
Provided the other 3 tires matched up to what the track was looking for, I doubt you'd notice anything, if you ended up with a handling issue it was because the other 3 were off.
My LF is usually softer and a more “all around” tire. I’ve been known to run ss11 left fronts from local short track racing a lot or a 33 even for 55 or indoor racing.