Red coupe wrote:its not the offset that matters, its spoke design. The spokes are mounted to the hub, so reguarless of offset they will still have the same clearance to the caliper.Its kinda a case by case basis youd have to test fit, or find out how much room you loose by switching to q brakes and then mesure what you have now.
It's actually both. Many manufacturers create more backspacing my having more material on the hub mounting point. With wheels that have a face that is fixed the backspacing would have the same effect on offset. This is particularly tru of most cast wheels. Multipiece wheels can mix and match a bit, but even then there are some center sections with more backspacing built in, that can affect offset.
As an example, I had some 40mm offset wheels that would not clear 300ZX brakes, but the 30mm offset version of the same wheel did clear it.