It really depends on the steering stops and the height of the tire. On my car the tires just touch at full lock, that's with 25.6" tall tires and a 6.1" backspace. But the steering stops on the lower ball joints are not all the same. I compared a bunch of old ones that I had and found that the height of the steering stops weren't very consistent, so, that effects where full lock actually is. You just have to kind of thread the needle between having enough space to the fender and the frame rail. Being too close to the frame rail is better, you can make some adjustments with small spacers.
In my case, I don't worry about it too much. With my 16:1 manual steering I'm very rarely at full steering lock anyway. If I were more concerned about it I could probably put a little weld blob on the steering stop, I don't have any more room to the fender to give up.
