Correct.
Spray the tyre & scrub, the solution will foam up as you scrub & with dirty tyres the foam will be brown.
Rinse & repeat until foam is white. I use a pressure-washer which helps but you should still get good results if you don't use one.
The initial cleaning may take 2-3 applications but after that once will normally do it & you may be able to drop back to 10:1, obviously depending upon your tyres, how often you clean them, etc...
I clean my tyres when I clean my wheels, every time I wash my car.
It is a good idea to have the face of the wheel wet before cleaning the tyres.
What sort of finish is on your wheels?
Clearcoated paint, uncoated polished alloy, etc?
I can honestly say I've never had an issue (clearcoated painted wheels) but it would depend on the finish of wheels.
Might be hesitant on raw, polished alloy, but this is generally only found on high-end race wheels, etc.
Hopefully someone with more experience of using SD on different wheel types can chime in.
I know BobbyG is another SD user & is a very switched on guy...