it took me a while to find reverse rims. They are not easy to source.
As for regular steel rims, I am sure that some board members have them laying around as many of us opted for a different style. I kept one of mine as a spare,
cheers,
Abel

Thanks Abel.
  Were do you find "reverse rims" or even just regular steel rims? the only steel rims I see are Cooper S. 
I will use what I have with the spacers, maybe buy spacers for front wheels to even them up with back wheels.
Ultimately I'd like to get back to the original set up.
I got the BMIHT factory record and it was built June 2, 1960 Austin 850 Super-de-Luxe model. 
 Cheers,
 Geoff

I have reverse rims on my car and, although the tyres stick up a little bit, I do not think  there is any need for arches,
with that kind of wheels,
cheers
Abel

S rims were designed to fit inside the standard body work... without arches.  

So you could keep the S wheels as long as you get the correct width spacers or even normal S drums - they will fit your 850 (use them both front and back..) You will also need to make sure the wheel studs are the correct length.

165 tyres will also fit...juuuuust..  The factory fit was 145s.

Cheers, Ian

I've heard of reverse rims. So to go without spacers I need to find reverse Cooper S rims or plain Mini steel rims.
 Thanks Ian!

S rear drums have built in spacers so the rear track will match the extra front track due to the discs.

Without this spacer S rims will not fit.

This why the so called S “reverse rims” were invented.  To give the S look to cars with stock drums (or the smaller Cooper discs).

Cheers, Ian

  My Mk.1 Austin 850 Mini had 12X5 wheels when I bought it. First thing I did was buy Cooper S white steel 10X4.5 wheel set from our sponsors. The car had fender flares and 1" spacers on rear drums. I am having body/paint work done, removing the flares, spacers and
studs so the car will look like a plain old 850 Mini.  
 Now the Cooper S 10"X4.5" do not fit, the inside of the tyre is hitting the trailing arm. What do you guys think is causing this ? 
Thanks