Should I buy Kevlar tires? How different are they?

is it worth the price of getting a folding kevlar bead road tire vs a wire bead version of the same tire?
main use of bike is for touring,
assuming a 50gm weight difference per tire,, how significant would that be for 50 mile tour?
another quesation is if you have a 700 x 23 tire inflated to 80-90 % max, vs a 700 x 25 tire inflated to max, what would the difference in ride characteristics between the two sizes, assuming both are of the same brand & model
thanks

1. 50g of rotating weight only matters if you’re racing and the competition is very tight or if you are doing a time trial. Other than that, it’s meaningless. In your case, I would definitely get the cheaper wire bead tire.

   For touring get the 25, unless you are really worried about speed. They can carry more weight and are more stable than 23′s. I think a deflated 700×23 will still not feel as good as a 700×25; if you deflate it even more you can get a pinch flat.