Which RS3 should I choose
 

My Dunlop ZII finally need replacing so I'm going with Tire Rack old stock RS3 for my next set of track tires. My track wheels are stock sport Rays.
So which combo do you think would be fastest on the RS3 tires on the sport Rays. I have a fully adjustable suspension front and rear.

245/40/19 front 275/35/19 rear
275/35/19 front and rear
275/35/19 front and 305/30/19 rear

Obviously 275 on the front or 305 on the rear is not optimal rims size but do fit.
I already have the two pairs of old stock 275 but Tire Rack still has old stock 245 and 305.

if you can fit it, go big. I run a 275-305 setup and it grips for days.

Yeah, 275F 305R for sure if you have a fully adjustable suspension. On stock suspension that will probably be way too pushy, but fine otherwise.

I would run 275 square Z likes rotation w squares

I went with the 275/305 setup. While I improved my best lap time by about 1.5 seconds over the 245/275 Direzza ZII the car felt sloppy and the extra weight could really be felt. The car oversteered for about a lap as the rears take a while to get up to temp. Once up to temp the rears overpower the fronts and I would get understeer. Once these tires are done I'm going to a square setup on 18" wheels.

Good luck finding 275 RS-3s....I've been trying to get some but everywhere I contact....3-6 month wait.