30% of 265mm is approximately the same sidewall height as 35% of 235mm. 35% of 265mm or 255mm would make the rear sidewall taller than the front sidewall - although, this would fill in the wheel well a bit more, but it would also increase your rake (rear end being even taller). It's also best to keep the overall rolling circumference as equal as possible (same sidewall heights) front and back to keep all the electronic nannies happy.
|