Help me decide

[rutthenut]

Garage door width and trailer-bed widths also need to be considered as appropriate.

Good points.

I built my car in a single garage and having Group 4 arches would've been tight.
Now, three decades later, I have a double garage but it isn't particularly wide and has two cars in it, so still no space for fat arches on either of those cars!

Have also seen those that need to trailer their cars around can find difficulties with the wide Group 4 rears. In some cases, they have to fit a set of narrower wheels just to get the car on the trailer. Some others have trailers or transporters that are wide enough.