Why do cars generally look funny with aftermarket wheels on a stock suspension, even at times when the wheels' diameter is the same as that of the stock ones? (Of course, I'm guessing that most people at least kept the overall circumference the same as stock's ...) I too a lot of times feel a car with aftermarket wheels need to be lowered to look "normal."

Is it just because people are used to the looks of stock wheels?

 

You pretty much answer your own question.

people usually lower their car with aftermarket wheel, you get so use to it that you kind of look for a drop when you saw someone rolling with aftermarket wheel.

plus the design of the wheels might have something to do with it, alot

 

It's all about the diametre and design of the wheels.

 

Color has alot to do with the look as well. I know a guy with an Berlina ap1 with black wheels, he looks lowered. I don't think that the dark gaps show as much.

 

Stock = Tire height larger than fender gap = normal

Larger wheel = Tire height smaller than fender gap = funky looking

 

It is due to a little something called fendergap. This ungodly sight gets multiplied once you put on a larger rim with a smaller tire, and therefore one should never put larger rims without a drop.

 

It's not always about plus sizing the wheels... my 17" volks make my car look like a 4x4 compared to my OEM 17's.

 

Lower profile tires also sort of create the illusion that there is more fender gap.

 

IMO it's the offset.
Most (if not all) aftermarket wheels have (far) less offset compared to the OEM wheels => make them stick out more.
And because most people get wider wheels then OEM they stick out even more.

 

100%. I've seen different sets of wheels of same dimension except offset put on the same car. The set that has the highest offset (tucks in more) makes the car looks more lowered.