[Piwoslaw]

Since my tires may need to be replaced within the next 1-2 years I'm starting to look around for the next set, just to know what is available. My car came with 195/65R15's (205/65R15's were an option) and this is what I use for most of the year. Winter tires are 185/65R15 and won't be replaced any time soon.
I haven't found low RR models any taller than what I have, and the only widely available tire with a higher profile is 185-195/80R15, but these are mostly for delivery vans. There is no mention as to what their RR is.

Switching to 185/80R15 should lower engine rpm by ~6%, and maybe slightly better comfort on bumpy roads, but will raise the car by ~20mm. I would benefit from the larger wheel only when cruising, not when coasting in neutral (which I do more often).

If van tires turn out to have worse RR than normal tires, then is the switch to taller a bad idea? And how much worse can their RR be to still allow me to switch to 80's?