Been mssing with gearing commander (gearingcommander.com) as I changed gearing at Cadwell and was interested the differnece it made to top speed. What I didnt realise as much is the difference a tyre makes. Running 200x60 gives me 10mph more at 12k revs than std 190x50, so park straight 12500 on 15/45 (-2/+3) meant 166 where the std tyre gives 154! Ended up on 15/42 and 12k before the brakes about 168 Worth checking if you change tyres on track as it makes such a large difference
