Guide to 15" Audi rims that fit over Subaru 4 pot brake

too much work for me

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Hi everyone,

It has been a while!

Just wondering how you are going with the Audi rims? I am looking at dropping down to 15" wheels to use the trepadors. I assume these are the same:
https://www.gumtree.com.au/s-ad/west-pennant-hills/wheels-tyres-rims/audi-a3-rims-and-tyres/1082817267

Also I have read elsewhere that the 00-02 forester limited 15" wheels will fit over the SG brakes. Can anyone confirm this? I haven't upgraded my pots to WRX ones. Like these: https://www.ebay.com.au/itm/98-02-SUBARU-SF-FORESTER-15-INCH-MAG-WHEEL-/261757156023?pt=LH_DefaultDomain_15&hash=item3cf1f13ab7
 
yep, those are the ones. Ridiculous price!
 
I might be able to do a weekend trip to pick them up. Need muddies since buying a block of land, keep getting close to bogged with the ATs
 
^ beat me to it. was going to buy them as spares.
 
Did anyone find a source for M12x1.25 R13 ball seat wheel nuts?

My preference is to find the correct fitting nuts.
Failing that, what is the best backup plan out of using R12 nuts versus conversion washers?
 
R12 wheel nuts are definitely the best option. The washers are much more likely to fail.

Alternatively you could have the wheels machined to accept standard conical nuts. Stuart has that setup on the AORC brumby and hasnt had any issues
 
Extensive googling of Audi sites would had me believing that the OEM Pepperpot wheels on early A3's are a R13 radius (ball) seat.

So I figured I could test this with an experiment at home. I needed a 24mm and 26mm sphere with a screw drilled into one side for a handle. The idea was to cover them in wet enamel paint and push them into the rims and see how much surface contact was getting made.

The plan came somewhat undone when I could only find a 25mm ball sinker for the experiment. So I tried this and amazingly the 25mm ball left a perfect contact print with the seat on the rim. This adds some credibility to Nachala's R12.5 theory. Only that doesn't really make sense to mix a metric M12x1.25 thread with an imperial seat.

I also tried making various molds of the rim seat with plasticine which worked fine but it's practically impossible to interpret anything from the mold as it two arc segments so I don't know what the radius of the segment is (if that makes sense?).

From the ball and paint experiment, I'd be more comfortable with an R12 nut than a R13 nut, as at least I know the R12 will be pulled down hard in the base of the seat. The R13 would sit higher in the seat and have to deform the alloy rim to pull down tight.

I'm still not against conversion washers but the suppliers don't be very specific in the sizing guides, they seem very generic IMHO.

So that only leaves the M12x1.25 R12 nuts from Otis, which are expensive but maybe the only option in this odd size. It appears the radius seat is a European thing which tends to go with M14 lug bolts and 1.5 pitch threads.

Don't you just love customising cars?
 
could always drill out the rotor hats and use M14 studs..
 
duncanm said:
could always drill out the rotor hats and use M14 studs..
Click to expand...

That may well be the safest option. The 15" pepperpot wheels were OEM equipment on the Audi A3 8L, this car used a M14x1.5 R13 lug bolt.

I did another experiment tonight using 24mm and 26mm discs which I fashioned using a compass, scissors, plastic and check with verniers. That left me convinced the wheel seat has a radius of 13mm. The lug hole is 15mm.

So by using an M12x1.25 R12 wheel nut on our Foresters we are not properly fastening the wheels the rotors. Is that a problem, I don't know? I abuse my wheels pretty hard at times and don't exactly want to crack one or have a studs break. That said, members have been running this combo for some time with no reported failures.

As it turns out though M12x1.25 R13 wheel nuts are just as hard to find as M12x1.25 R12 wheel nuts.

The hardest thing of all to find are M12 60 degree conical seat to M12 R13 radius seat conversion washers!
 
option #372 would be to turn/machine a R13 seat in readily-available conical nuts.
 
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