It is impossible to say without seeing picture or measurement. All Minis from the 90s on had factory installed wheel arches to cover the then standard 12" wheels. Of course, the Sportpacks have the larger arches with trimmed body work as Dan mentioned. Outside of them, the others all had factory drilled holes in the body work. The arches you have on your car now could be using the factory holes, or more could have been added. My car came from Wood & Pickett and had their arches fitted. They mount to the lip of the wheel arch and not with drilled holes BUT the factory holes were still there when I went to bring the car back to a more stock appearance. 

 

Something to note about factory plastic arches, they can and were painted. My Monte Carlo came with factory painted arches, as did several other LE models and. JCG conversation. Painting them to match the body color really levels things up a bit.

I don't know beans about Japanese Minis, and I ha e no Idea of what you consider crappy. But there are some things to watch out for:

The first one is a Mini with 13" wheels. They don't fit well under the standard wheel openings of the steel wings/fenders. "Sportspack" Minis came with 13" wheels, so the add-on plastic arches were designed to accept the wheel size. That meant the front wheel openings were enlarged by about 1" all around. If the car didn't originally come with 13" wheels and someone put them on, they would have to cut the steel fenders and install the larger plastic arches.

The second issue is wider tires/wheels. Most jurisdictions have limitations on how far a tire can protrude beyond the wheel arch or fender - that is why plastic wheel arches became standard. If you research on the many styles available, you will see arches extend anywhere from about 1" or so to 4 to 5 inches. And then there's custom work....

So, decide what you like and get a Mini that has arches that suit you, or at least are very close.

In the attached photos of my Mini from the mid 1980's, you can see the stock wheel arches. In the front view, you can see how much the arch extends to cover the tire. It has stock 12" alloy wheels over disc brakes (front) and spacered drums (rear), which are also stock for that car. 12" rims were required to fit over the 8.4" diameter disk brakes, which pushed the wheels out a little. The back drums have built-in spacers so the rear wheels match the front.

So, you can see that the shape and width of the wheel arches is more than just style.

Hey All,

I'm currently searching for a Japanese Rover Mini and I've noticed that changing the wheel arches seems to be prevalent.  Either for style or wider tires, not sure.

Either way, I will probably be interested in either swapping them to something less dramatic or back to stock. Does anyone have insight on this?  will the aftermarket arches cause holes that will need to be filled?  are the holes in a "standard" location and size that other arches will fit?  

This question may determine which car I buy.  if the car is in otherwise great shape but has crappy-looking arches, it would be a shame to take them off and have to fill holes and paint.