Frustrated with gas mileage

I own a 2010 Prius III and have about 47,000 miles on it so far (I do a lot of driving, I know!).

Recently, I had my tires replaced and have had the 45k scheduled maintenance completed on my car but my gas mileage has been horrible since replacing my tires. My wife and I just took a road trip to eastern Washington (where the terrain is mostly flat), and I averaged since the trip around 43 - 45 mpg. Before replacing my tires, I was getting the normal 49 - 51 mpg since April when the weather warmed up. This past winter I averaged around 46.5 - 47 mpg. The gas mileage has been AWESOME up until the recent tire replacement. I love this car, and how it's helping to reduce CO2, but it's frustrating when the mileage isn't where it *should* be!

I'm wondering if anyone else has had this same issue? I've taken my car to a dealership to get this checked out, who did a quick check on the tire pressure, fluids, air filter, brakes and found nothing wrong. They basically said that unless an alert is showing on the display, there's nothing wrong with the car. But, I still have the reduction in gas mileage.

The only variable is the tire replacement, which I've heard could cause more resistance on the road.

If anyone has heard of this kind of issue, please let me know.

Thanks!

What was your original brand of tire and what pressure were you running? What is your replacement tire and what pressure are you running? You may safely fill up to the sidewall max. pressure. Some of us are willing to take the compromise of a stiffer ride and go even higher. It is of course your choice.

PA P

New tires require a breakin period before they will deliver their maximum performance including mpg. This applies to every tire on every vehicle.

A common mistake Prius owners often make is buying a non- LRR (low rolling resistance) tire as their replacement. Because the Prius comes equipped with LRR tires, if you replace them with something else of course your mpg will drop, especially before the tires break in.

Another factor is rolling diameter. A pair of bald tires are usually smaller in diameter than new tires of the same size. This will cause the odometer to read faster and may cause the mpg calculator to read artificially high.

Please provide the info requested above so we can help you further.

I replaced the factory Yoko Avid 195x65x15 with Michelin Energy
Saver tires. I noticed a 2-3 mpg increase. I purchased at Costco
and all four tires are filled with 44psi of Nitrogen which is the max. sidewall pressure for the tire.

In the past with my Honda Civic 1994 VX model I noticed a drop in MPG's when I replaced the factory tires. So depending on the tires you purchased there are a few variables that will effect MPG's.

alfon

Yes, please provide info as requested in posts 2 and 3, otherwise we have no idea and flying blind.

Even if you changed them to identical tires, see Tire Tech Information - Tire Rolling Resistance Part 3: Changes to Expect When Switching from Worn-Out to New Tires.

You might also want to verify that they used the recommended 0W-20 synthetic oil for the service you had at the time of the tire change. Others have reported a significant mileage hit with substitutes.

Grrrr. I wish I could get the 46mpg that you are getting. My Prius has only about 6,000 miles and gets no more than 36mpg. We live in San Francisco, which is going to reduce mileage because of the hills, but I was in a Prius taxi recently which displayed 44! In a cab! As I said, grrr.

When dealers measure pressure they often lower it to the Toyota recommended value. You can safely increase that to the max shown on the side of the tire and get noticeably better MPGs. Of course, as noted by others, if they're not LRR tires then they'll never be as good as the originals.

wow truck51. that is not good. I got 38 in dead of winter with temps in single digits and a couple of feet of snow on ground... You might want to check out that car... Especially if a cabbie got better mpg..

I mentioned it to the dealer at 4500 miles and he said the car was still being broken in. It's 1000 miles later and no change. Do you think he's correct about break-in time?

No way...break in is good for .5 to 1 mpg tops...if that.

I got hosed with some non LRR tires even though the lying liars at Michelin said they were. You CAN get good FE but it is really touchy.

We are "down" to about 45mpg but do the math...not worth it to mess with the tires. Also note that right before you change your tires you will get the best fuel economy ever I suppose due to their lack of tread and smaller size...we even got 55mpg calculated which makes you even more mad when you lose 10mpg but reality is we were probably around 47ish (I never really tracked prior).

It will loosen up a bit but I guarantee you can find a sweet spot, last week my gage was at 45 and I was able to get it back to 46.2 with some careful driving.

Picked my up from dealer today, only has 90 miles but I'm already up to 48.2, it may have helped that I am used to driving a Prius, flipped my 2010 and got a 2011.

Running air or heater all the time?

I think your mpg is a result of very short trips and the hills. Breakin will not have a profound effect on mpg.

I agree w/F8L.

As I directed the OP as well, please answer the questions at
http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html.

Most fuel-efficient cars is what CR got in comparison.

I was just driving in SF last night and was averaging upper 30s at night. So, there's probably nothing wrong. There are lots of hills, lots of traffic and lots of traffic lights.

Sent from my MB860 using Tapatalk

I believe that the cab with a warm engine 99% of the time explains the diff.
Hills kill mileage but so do short trips.

It's all in the tires if you go from LRR to standard.

My Girlfriends 2009 prius went from factory tires ( 57 mpg summer time ) to standard tires ( 54 mpg summer time ).

My Fathers 2005 prius went from factory tires ( 51 mpg summer time ) to standard tires ( 45 mpg summer time ).

I still have my factory tires on ( 60+ mpg summer time ). Only have 10k miles on my 2010 prius so far but i'm sticking with LRR tires when the time comes to change them.

I can confirm from my experience that a bad tyre choice is good for a 15% hit in MPG. I did it with Falken Zi-Exs a couple of years ago. I had researched the tyres and was not expecting a high grip tyre, but I think Falken changed the formulation.

I didn't believe at first it was the tyres, and kept going back to have the alignment checked. Eventually (and I mean *months*) the MPG slowly returned to usual. The tyres only lasted 40k miles, pretty good supporting evidence of my poor choice (as if I needed any more!)

Well the factory tires are only good for 40k too and that is pushing it.

But the taxi i rode in showed 44mpg. And he's taking hills way more than I am.