To predict a change in bike low end performance from installing taller tires, measure your current tire true diameter.
To do this, roll the machine one tire rotation and measure the distance traveled. I put the valve stem at the bottom and mark the floor, then roll the machine until the stem is at the bottom again and mark the floor again, then measure the distance between the marks. That is the true circumference, to be put in this on-line calculator. Hit the calculate button for the true diameter (tire height).
Circle And Sphere Calculator
Other members can give you known diameters of tires they run that you are interested in.
Many tire models have stated size that is not actual when mounted.
Much of the low end power lose is from the added rolling resistance from taller tires. I calculate the percentage difference between tires diameters. If the difference is say 10%, raising the pulley ratio by the same 10% gets the low end performance back. If shims are used for this mod, the shims are a linear mod meaning what is added to the bottom is taken from the top because the shim mod moves the entire movable sheave away from the fixed sheave.
That is why COOP's machining is popular, as he changes the sheave face angle which removes material from the center of the sheave to enhance low end performance, but leaves the outer sheave surface alone for no reduced top speed reduction.
If you want to go with the shim mod, which reduces the top speed, cutting the cam plate can get the top speed back.