[QUOTE=AU Tiger;21604146]+1
Several years ago I went from the stock 28mm tires that came on my Fuji Absolute to 35mm tires. What an amazing difference in comfort, and my speed actually increased. It's possible that increase was due to other things, but I do believe that the increase in comfort and confidence in traction made me more willing to go faster on downhills. I would be very surprised if going from 35 to 32 would, by itself, produce any sort of significant increase in speed. As others have mentioned, I think tread makes a bigger difference.
Great advice........I rode 28's for a time at 110psi and thought I was speed racer until I needed to stop or turn or hit a dirt patch or hit a bump......back to 35's and will never look back