Given the small variance in tire diameter, and the fact that the wider front tire may be stretched over a large wheel, you may net out very close to even front/rear rolling diameters.
The only oddity here is the “why” behind the need to run different widths when you have all the adjustments available to account for handling disparities that you’re trying to solve for. Spending more money to do it this way, rather than use the upgrades you have available is just a different approach than I’d expect. I am not flaming you, I am simply questioning the thought process.
A wider tire/wheel/offset combo on the front axle introduces a different scrub radius, and the varied track width front to back is going to have implications on handling (in this case, it would be more mid corner understeer on power). If you wanted more mid corner understeer all along, there were way easier methods in accomplishing that. In addition, one can fit 275’s on all 4 corners without rubbing for track use-- 18x9.5 wheels with 275 RS3’s have been done before. With that in mind, I do not see a reason to run staggered if you can run equal widths all around. Also, if one is not competing, I really question the aero drag arguement. One needs to develop a lot of notes and testing to determine that a reduction in mechanical grip at once axle is advantageous given the difference in drag. AND–those aero advantages are only valid at very high average speed courses. FWIW my avg speed at Mosport is something like 155kph or so (going off memory here!)–and that’s supposed to be the 3rd fastest track in the world. Drag matters there, sure. Other places? Nope. And drag is really a concern if you are racing under a governed rule where each car has to run an inlet restrictor–so you’re down on power. You don’t have any of these restrictions.
And lastly, the car is only as good as the worst axle. If you have reduced grip on one end, you will always be operating under reduced grip, as you will always need to compensate for it, and the limits of adhesion are always going to give up on that same axle–yielding a compromise in driving and handling. You already have decently high rear spring rates on an axle with near 1:1 motion ratio. Adding more rubber up front in my mind is only yielding you 1 single advantage that no other adjustment you have can be made to account for–and that is increased grip under braking. That’s it.
Also, look under any awd redline world series time attack car. They run square setups for the reasons I mention above. Trust the guys who document this stuff and test these things furiously. These are full aero cars which still choose to run square setups. If you’re concerned about aero, throw on some fender flares and canards infront of the wheels. Stick some air fences where the wheel portrudes and connect it to the splitter etc etc.
