My CT is lowered about 1" in the front and 3/4" in the rear. I was wondering what range of offsets on 17x7.5 wheels would fit without rubbing, issues, or needing any spacers.

 

It is not an issue. Stick with the stock offset. Your loweirng is not much different from my old 2012 CT200h F-Sport SE which was lowered quite a bit from the factory. I think the 2012 SE model actually got lowering springs so before anyone posts that the F sport is not lower, my 2012 SE was a lot lower than a normal F Sport. They only made 930 of the SE model. It also had a unique color interior.
Your wheels are not wide enough to affect anything.
Also try some searching as I suspect this has been discussed already.

 

Yeppers the SE's came with blue f-sport lowering springs along with blue f-sport sway bars from the factory.
But normal F-sport aren't lower than a base CT. The blue f-sport lowering springs lower the car about 1", sometimes less. When I put the springs on my f-sport with all new suspension it only lowered the car about .5" and I wasn't pleased with the drop so went to Tanabes.

OP:
For the size wheel you really shouldn't have an issue with rubbing at all. You could actually get wider wheels which most folks end up doing. But at 1" lowered you aren't at all in the realm of anything rubbing. You'd need to be a lot lower than that.

-Nigel