I just got some new pilot powers front and rear. The stock size on the 636 was 120/65; the power is a 120/70. Do you think that will create any steering instability? When I initially got on the new tires the front felt higher and the steering was lightning quick. It's probably just the new rubber, but I could use some input. What a world of difference with some new rubber. I forgot how precise this bike turns in.
Well seeing as how the 70 series is taller than the 65, you should have lowered the front tree to make up for the slighter taller tire. However, I've had friends run 70 series tires on 60 fronts (early R6), and they didn't notice any instability or slower turn in. You'll probably be fine.