What size rims and type/size tires will give the best gas mileage for a 1st gen xb?

 

I would also suggest getting something lighter which would also help with less rotational force and better gas mileage.

 

When you suggested something lighter ,do you mean a lighter rim,like aluminum or an alloy/or are there lighter tires as well? Also I'm still wondering if height makes a difference?I believe I was told.,as an example, that a 14'' rim would get better mileage than a 15'' rim?

 

Lightest wheel, lightest tire, lowest friction tire (hardest tire). Research the factory equipment for the Prius; it may bolt up to the xA/xB/Yaris/Echo. I also suggest seeking out the customer service reps at tirerack or discounttire for information. They know their stuff.

Oh, and 15-inch Konig Heliums are only about 11-pounds a pop. They're also relatively inexpensive.

I'm not sure if ride height makes much of a difference. I suppose that, in theory, the lower the ride height, the less wind resistance will reach the undercarriage. But. . . the wind resistance is going to infiltrate the undercarriage regardless of height. What would really help reduce wind resistance underneath is some smo-o-o-o-othness, like the undercarriages of late model super cars, exotics and hyper-milers. Now, concerning wheel/tire height - the lower you go in comparison to factory spec, the more and faster your odometer is going to spin = the more mileage you will see but not truthfully travel = the more fuel economy you will measure but not truthfully achieve.