CMcNam

No, it will not change the gap except by a very small amount. The overall diameter of the tire will remain (mostly) the same whether or not you get 18s, 19s, or 20s. It's an optical illusion that 20s "fill" the gap better, they are the same diameter as an 18" wheel/tire combo. The diameter is around (I believe) 27" whether or not you use 18s or 20s, but it can vary a little bit.

If you want the wheels flush with the fender, then you need to be looking at the offset (how far the wheel is pushed out). That will be different depending on what wheel you get. For example, my wheels run a +35 offset and are exactly flush with the fender (they are also 9.5" wide), but if you have a 8" or 9" wheel it will be different.

I don't know the technical terms, so feel free to correct me.

Edit: link explaining tire sizes Tire Rack.

white08gt

19's would be the best bet. go with staggered set, AM puts the size tires that match closet to stock height so speedometer reads right. i am running one of their staggered sets. 255/45/18 front 285/40/18s in the rear. eventually i lowered just the rear 1" with Roush springs, leveled out the car. i am running the Nitto 555 and they are not very good in the winter, so pick your tire wisely.

AMDanBailer

In my experience, in order to get a good ride height on a Mustang you need to lower it. My 2011 GT came with the factory 19" Brembo wheels and still had an insane amount of wheel gap. After lowering my car on a set of Eibach Super Sports, I definitely have the ride height I think the car should have came with from the factory.

However, if you don't want to lower your Mustang I completely understand. I would go with a set of 19's or 20's to help fill out the wheel well as much as possible! Is there any specific reason you don't want to lower your Mustang?

-Dan

drukkosz

Is there a difference between 18 and 19in wheels? (Except visual effect). Like ride quality, noise etc

danzcool

If you go with a larger aspect ratio on a bigger wheel you can start to fill in the gap... or you could just donk it out with 22-26's and rubber bands (not my recommendation)

AMDanBailer

There's not going to be a noticeable difference between 18's and 19's when it comes to ride quality and noise etc.. If you were to jump from 17's to 20's, you'd definitely notice a difference. However, a 1" change is going to be noticeable! I've switched from 17's to 19's a bunch of times and never really noticed a difference.

I hope this information helps you out!

-Dan

drukkosz

Thank you Dan for your input. I am planning on purchasing a set of 19`s from you but havent decided on tires yet.

adidasUNT8

It's kinda like asking "What is your favorite color?"

lowering the car helps clear up the fender gap with the stock suspension and also helps with rollover. In my opinion the larger wheels will look worse without lowering it.

AMDanBailer

You're welcome! Definitely let me know if I can be of any assistance, I'd be happy to give you some recommendations.

-Dan

drukkosz

Dan I sent you PM
thank you