Spacer difference between 1.5 inches and 1.25 inches

I am currently running running 285/75/16 WildPeaks AT3W on stock rims, with a 2 inch lift and 1.5 inch spacers. Before the spacers, the 285's rubbed on the upper control arms at full turn. The 1.5 inch spacers solved that problem perfectly. But then the tires rubbed on the mud flaps because they sit out that much further.
How much difference would 1.25 inch spacers make? The sweep of the tires would be reduced a bit, but how much? Is the arc reduced by 0.25 inches X Pi (3.14?) for a 3/4 inch difference? That would be worth making the change, but only gaining 0.25 wouldn't give me enough room to put the mud flaps back on. (Canadian Winter is coming)
Thanks is advance to all of you who already hate stock mud flaps and also a big shout out to everyone who will suggest RokBloks. I am really just interested in the math to see what will be possible. Will that quarter inch at the hub make a difference at the outer edge of the tire?

 

As a good estimate, can you simply turn your wheel full and then look at the clearances? The tire is going to move 0.25” orthogonal to the axis of rotation (towards hub of course).

 

It's not easily calculated since it's not turning on truly orthoganal axes.
It's a compound angle determined by caster(ex: 3 degrees) and SAI(ex: 12 degrees).

 

I am thinking of writing a matlab code to calculate tire fitting/rubbing by tire sizes. Maybe I can compile it so people without matlab can run it.... hmmm

 

About .25” difference.

 

You beat me to it!

 

Once it’s fully turned, simple math says move it in 0.25”. In= 0.25” in the direction towards the hub. Yes, that effects the overall sweep. But we’re dealing with tenths of an inch here. The ol’ thumb perspective aught to be pretty close.

 

Oh, I agree...
Don't mean to come off pedantic.

 

No worries. I stress over stuff myself all the time. Too much of my life is wasted on that stress.