[FKHeath]

If you did put this size on your RAV4, can you comment on ride quality, MPG difference, and anything else you think relevant? Do they look better?

Size has little to do with those qualities. Other differences have a bigger impact: tread pattern, manufacturer, load specs (SL vs XL), speed rating.

 

[FKHeath]

If I was to choose an all season tyre in that size, I'd go for the Michelin Primacy A/S. That tyre is known for its mileage and comfort.

That is what came on my RAV4 from the factory. Yes, they were good riding, but were terrible on snow and ice; traction on dry pavement was just so-so. Highly not recommended if you live where it snows.

What you gain by running the 245 aside from a taller sidewall, is the ability to lower tyre pressure a bit - about 2 psi. A tyre with a larger volume normally runs slightly less pressure.

Both Tire Rack and Discount Tire, on their web sites, have charts for the tire pressure you should use when you use different size tires. The tire pressure you should use is determined by the weight rating (molded on the side of the tire). Even for the same size tire, the weight rating may differ if the tire is an SL (standard load) or XL (extra load) rated tire.