20 " wheels and lowering springs
 

So I have a 2013 Acura TL SH-AWD. I am looking to put 20" rims on it and a set of lowering springs. What is my best bet for wheel size, tire size, and lowering height without any rub?

since, EVERY one's set up will be different, it will be hard to tell you.
you will need to figure out how low you're dropping, then use math to figure out how much offset and width you can go with wheels.

wheels aint a joke. you'll need to put in the required research in order to get the right set up.
so, this means studying different set ups

and all depends ON YOUR GOALS!

What I'm looking to do is put 20" Rims on the car, lower it so there is not much gap in the wheel well, and no rub. Just was wondering if I dropped it let's say 1 inch with springs, could I fit 20"s without any rub. Not looking for staggered or anything like that. Am I better off just getting the rims first and see how it sits before I drop it then see what kind of clearance I'm working with?

it would be better to set the prefered height first, then you can play with width, offset and tire dimensions

check the this thread 4G Wheel/Tire specs thread with pics. check. You'll see what works without any modifications and what wont.