what size for ultimate handerling?

[evilC]

i agree with $aint on this one. The larger wheels are to allow the potential for super sized discs since they can't run carbon rotors and in general their weight restrictions optimise around the larger discs. With the lower classes there is a bit of blind following but don't forget that modern wheel sizes are tending towards the 17"+ diameters. I think that you shouldn't buck the trend as it will eventually restrict your options. I would go for 17" wheels if you are committed to the 650(ish) rolling diameter. You then have another option at a later date should you need to lower the gearing - fit 15" wheels with low profile tyres @ say 580 rolling radius.

BTW low profile tyres/large dia wheels are heavier than high profile tyres/smaller dia wheels for the same rolling radius so the low profile route will increase unsprung weight that on the front of a bug will have a significant effect. Mind you unsprung weight never slowed the Mk1 and Mk2 Escorts that 30 years on are still winning!