[Ghetto2315]

Not sure if anybody knows the answer to this but if you look at the diagrams above and you see the diameter for Size 1 and Size 2 and then % diameter difference.

If going to non-OEM tires like we all are discussing, do front and rear tire both have to be -% or -% (or +% and +%) or can front/rear can be -% and +%? The reason why I ask is because the % diameter difference plays a huge role in speedometer accuracy. If the front has a -% and the rear has a +% (or vice versa), does that cause an issue?

EDIT: For Example. If you go to a front 235/40/20, it is a -0.7% diameter difference than front OEM. So the speedometer will read slower than OEM. But if you put rear 255/40/20, it is a +1.1% diameter difference which means the speedometer will be faster than OEM.