I wanted to do something similar, but the folks at the tire shop adamantly discouraged the idea. Even though SUV's like the Porsche Macan have a staggered tire setup and are AWD, the Evoque's transmission is not built/programmed for the same tolerance - supposedly. I have the stock 245/45/R20s on my Evoque. I wanted to go with 275/45/R20s on the rear and keep the front stock. They advised against even though the only difference would the width of the tire (no change in diameter, circumference, sidewall, or rev/mile). They still advised against going with different sizes from front to rear.