Bert,

I am sure you probably already have this but I have 3 gearing charts for the 3 different tires brand/sizes I use. I keep track of how many shifts per laps based on gearing of each tire. I also did some rough calculations based on timed gained by using lower gears versus the extra shift. I had previously run a 4.11 rear gear but went to a 4.38 and smaller diameter tire as I was nowhere near redline in top gear. It also allowed me to drop down a gear in a couple of places and get a better drive off the corners. The extra drive also helped out top speed wise on one of the long uphill straights as the car tends to hit the aero-wall, granted it was barely 100 RPMs more but every bit helps.

Before you flair the guards have you given thought to just running the taller tires on the rear for faster tracks and using a slightly different offset wheel?

Tom