It has to do with harmonics of the valve train if you are at 4k rpms... the frequency of the springs can still float depending on ramp and duration of cams. I would rather be safe than sorry and just get new bee hives, but that's just me.
Ok so my plan is to run 225/40 up front and a 255/35 in the rear. The is a -0.24% difference. Or 0.06 of an inch as shown in the link http://www.1010tires.com/Tools/Tire-Size-Calculator/225-40R18/265-35R18/255-35R18
As for the rims they are SSR AGLE strusse from Japan when I was stationed...
Here are some pictures to see what they look like, don't mind the nastiness that is my car it's been sitting for around 7 years and just starting to restore it.