here is the rear fender from one of my bikes that only has a rear fender, 28s, a fair amount of clearance near front of tire, and it gets less as it goes along, to little near rear of tire.
other shot is my old tourer, with the front fender. again, varying amount of space.

camera angle plays a big part in giving an idea of space between tire and fender, I put some white foam core behind bikes to help, but camera angle very much plays a part in it.
Bottom line is that on both bikes, there are parts of the fenders that are much closer to tires than others, but in regular riding on varying surfaces, fender/tire clearance hasnt been an issue.

take all this with a grain of salt re your riding.