MPG drop with touring wheels?

[barryjkaufman]

Max: I see you're in LA also. I looked all over for the original 195/55/16 tires and as you also notice the pickings are pretty slim. I hit something last Friday night and my tire was flat within 30 minutes. So I didn't have lots of time to go shopping. And since I had 40,000 miles on my Prius, it was time to change the tires anyway. It was a toss up between Big O Tires and Costo. The Michelins at Costo were in the $150 range and Big O had Falkens closer to $110, both in the 205 size. Big O also had Firestones in the 195 size, at the same price. Since the Falken was a better tire I opted for them. Of course when all was said and done with installation, tax, and a minor front end aligment, it was still $600 by the time I was finished.

At first glance the car is a little quieter on the freeway, and the ride does not seem quite as harsh. And you know how some intersections hump to drain the water, the new tires definitely make a difference there. Its not a jarring when you go over them. The real test will be in the wind and rain. I had some pretty scary moments on the I 5 between LA and San Francisco.

I was averaging around 48 mpg around in town on surface streets and the freeway. Of course it's tough to do more than 50 on the freeway during the day. Remember that heat wave we had a month or so ago. The temperature was over 110 in the Valley and I barely got 39 mpg. But everything went back to normal when the temperature cooled down. But driving to Las Vegas, Phoenix, and San Francisco, I would average anywhere between 42 and 44 mpg. I reset the screen after each fillup so I would know when to refill the tank. At 48 mpg I would refill anywhere between 400 and 430 miles. But on the open road when I average in the low 40's I refill the tank between 350 and 400 miles.

I'll let you know how the mileage changes as I break the tires in.

Here's another web site that calculates the difference in speedometer readings for different size tires. Tire size calculator

Barry

[barryjkaufman]

I have over 2,000 miles on my new Falken Ziex 325 (205/55/16) tires and my mpg is beginning to settle in back to where it use to be. I'm back averaging around 46 - 48 mpg on each tank around Los Angeles. And I was pleasantly surprised at the increase in mpg on the open road. I use to average 40 - 42 mpg between Los Angeles and Phoenix, which includes climbing a mountain or two and I averaged 44 mpg both ways on my last trip.

[Orf]

I do not know about the US Prius but my Ossie Prius has a setting on the MFD for tyres. I can select either 15" or 16" and reset the calibration when new tyres are fitted. I suspect that the Prius continually recalibrates tyre diameter as the miles are clock up to correct distance travelled.

[KandyRedCoi]

simple: touring wheels and tires are bigger and heavier than the standerd 15", hence the drop in MPGs

[bac]

Originally Posted by KandyRedCoi

simple: touring wheels and tires are bigger and heavier than the standerd 15", hence the drop in MPGs

Yup, that's the bottom line. He had an odd tank of 30+ mpg, but that was just that.

Better MPG Tire = Skinny - Hard compound - Low weight
Worse MGP Tire = Fat - Sticky - Higher weight

There is a trade off between performance, and fuel economy. Choose what's best for you.

... Brad