What were the original tires on our Toyota Prius 2019. 15 inch tires, “routine” trim, nothing fancy. We had the same problem referenced on the April 14, 2019 Dear Car Talk - had tires replaced and milage plummeted. Tires were put on by the dealership too! Turns out they were not the factory installed originals.
No idea, but what I’d do as a start is to open the driver’s door, there should be a sticker on the door pillar showing the recommended tire specifications. If you need more info than that, like the originally installed tire brand, your best bet is to ask at the dealership, or at Toyota corp. (The original tire brands probably change all the time so the actual brand may not be possible to determine).
The mpg went down significantly after installing new tires? By what %? How are you determining mpg? An mpg measurement requires an accurate odometer, so that should be verified before going down any long diagnostic roads.
View the available tires shown on Tire Rack web site, select “Original Equipment” to view factory spec. tires.
Did you select replacement tires based on price or features?
3 Likes
It was dealership recommendation!
I worked with eight service advisors who would simply show customers a display of the tires we had in stock and the prices. None of them were prepared to discuss rolling resistance. Most customers are interested in cost and tires wear life.
Is the fuel economy reduction significant? If your fuel economy changed from 50 mpg to 45 mpg, what is your increase in annual fuel cost?
It was 8 MPG and we drive about 20,000 miles a year, mostly on 45mph country roads and interstate
The Ecopia EP422 (the 422 stands for earth day) is a low rolling resistance tire, if it was replaced with a standard tire then you will loose fuel mileage… The Ecopias are Bridgestone’s flagship of low rolling resistance eco friendly (as much as possible) tires…
Was told that by Mr. Gary Garfield in person while we were doing some work to his daughters vehicle… lol
I thought I’d chime in. I’m blessed with being a tire tester for Car Talk and another publication. One thing I have learned by doing the research before writing a lot of test reports and reviews is that nearly every brand offers a 30-day or 45-day “Return them with no questions asked” policy. If the tires are ones you don’t like, that may be an option. You will pay for mounting and balancing of the replacements, but you can swap to a new tire model without any fuss at most retailers. Choose a model that advertises efficiency. Tire Rack is a good resource (even if you are not buying tires from the company).
2 Likes
Huh? A Prius should not get 8 mpg even dragging another Prius.
If you or your dealer reset your average mpg meter in the car, ignore it for now, it will improve.
I think they meant 8 mpg less after new tires. Of course not telling how they check the mpg or what the new tires are.
I think you are correct that they are just going by the dash readout.
4 Likes
Double check the tire pressure first thing in the morning to make sure it’s at spec. I run 2 psi above sticker spec
1 Like
You are correct, I was just going by the dashboard readout, and “*” was the delta between the two tire brands
So many variables with a hybrid. Did you measure this over the same type of driving conditions as the old tires? With a hybrid, your fuel economy will be all over the place unless you’re comparing the same driving conditions with each set of tires. Rolling resistance alone is not going to make an 8 MPG difference.
New tires, even good ones may cause a bit or a loss in mpgs simply because they weigh more and the tread squirm from thicker tread depth creates drag.
But the Prius does come with low rolling resistance tires that are more expensive than average tires. Most people buy tires on price and the dealer knows that.
1 Like
It’s not a new complaint with the Prius and new tires, we had a set of Michelin Defender XT’s on our 2010 that got the same mileage that the OE’s did. No difference over 10yrs.
What are the tires you have now? Tell us brand, tire model (like ecopia), tread width, and height. From @Nevada_545’s post that would be 195/65. You can provide the rest of the size code too if you like (e.g.195/65R15 91S). The codes may be the same or not, but it helps figure out whether the tire is low rolling resistance or not.
I think this is another person who does not understand how and what the dash read out does .
1 Like
They are defenders 195/65R15 91H
1 Like
Then they should meet Michelins Green-X low rolling resistance objectives…
I found, with my Accord at least, that the longest coasts (least rolling resist) down from a set speed occurred with the cold tire pressures set from 1psi below to 1psi above door frame placard specification (32psi in my case).
That’s 31-33psi for my 2010.
At pressures below that, the car coasts down from 40mph a lot quicker, for obvious reasons.
At pressures above that zone, for reasons more complex, coasts are also marginally shorter: because over-inflated tires are less compliant, and tend to skip more over rough pavement, manhole covers, and other imperfections.
Hypermilers, you have been advised: Inflating your tires to 43psi cold or 50psi cold will experience diminishing MPG returns. Just not as severe as letting cold pressures decrease more than 4psi below vehicle placard specs.
1 Like