I see the Prius 4dr Touring Hatchback is available with 16" Standard and 17" & 18" available as Optional wheels/tires. I'm guessing the larger the tire, the more comfortable the ride. How bad a hit on the MPG does the car take when using 18" as opposed to 16" wheels/tires?
FMB (North Mexico)
According to the Toyota website, these are the available wheel/tire sizes for the 2008 models:
P185/65R15 P195/55R16
According to this website, the 15 inch wheel/tire combination is 1/10 of an inch larger diameter than the P195/55R16.
A smaller tire should be better, years ago I went up about 5 sizes on a big 4x4 and lost maybe 20% milage, original tires on it were undersized. But weight is a big factor, I would think toyota would know exactly how much different
Did you recalibrating your speedometer/odometer? Increasing the tire size will make the speedometer read slow and the odometer read shorter than the distance traveled.
All other things being equal, larger diameter tires should result in reduced rolling resistance and give slightly better mileage.
Jack
Larger tires have more rotational mass that takes more energy to get moving and slow down, larger tires change the gearing both will loose you mpg as you will never see the real large tires as an option as you do on other makes, larger tires lost me alot of mpg, pickup, and braking, best mpg would be a thin tire with hard compound.
Both the Prius models that have P185/65R15 (regular model) and P195/55R16 (touring model) have the same EPA mileage rating.
Thank you all for your input. I appreciate it.
FMB (North Mexico)
The use of low rolling resistance tires will make quite a bit more difference than the small change in size. IE: the goodyear integrity is a low rolling resistance tire.. That's why they use em on a lot of the new cars.. Helps them squeak through the gov regs on mpg.. The Corolla uses the same exact tires.. Same size too.. So when I get new tires, which happens to be soon o-clock, I'm going to stick with low rolling resistance tires. I really do think they make a difference. IE: my corolla will coast a real long way vs some cars/tires.. I think the tires play a fairly large part in that. I've heard a low resistance tire can have 20-30% more drag than some other regular type tires. Which in the real world may mean 2-3 mpg extra. No matter what you run, the higher the pressure, the lower the rolling resistance. Although the integrity gets some pretty lukewarm reviews, I might stick with em, just to keep the low resistance. And, actually I haven't really had any particular trouble with them. I'm clocking over 43k on the original set and they are still going. They will cost me about $30 bucks a tire more than a cheapy $60 special, but I hear the cheapy tires can really jack the resistance up a bit. I've read reviews at tires.com from some drivers that actually noticed the difference in mpg and commented on it.
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