Did I buy the right tires?

I'd drive it for a week or 2 - then see what they're like. New tyres need running in - they used to say 1000km.

Do they grip better - more sporty? Possibly you're "enjoying" the new feel and driving a bit more aggressively?

 

If getting the best fuel economy is key (and that’s why I bought the car) it is not the right tire. The defender is a good tire but it is not a low rolling resistance tire (LRR). A Michelin Energy tire or the Bridgestone Ecopia’s would be a good choice to maintain the fuel mileage you car was designed to provide. I have the Ecopia’s on my Prius Prime and have been very pleased.

 

Did you change tire size? What brand tire did you replace?

The tire shop might have a return/exchange policy. I wouldn't hesitate to ask, now, before you put more miles on the tires.

 

There is a very small change in rolling radius between various tyres - you can check if your speedometer has changed by checking it against a GPS (or smartphone). I've had up to 2km/hr difference between old tyres of one brand to new tyres on another brand (not on a PRIUS, an old VOLVO). Which would have a small bearing on l/100km.

 

The weather where you live has gotten colder recently, right ?
Pay close attention to your tire pressure and consider running them about 4 psi higher.

 

Your current tires might be a good choice despite impact on fuel efficiency.

Consider that the Defender is rated for 145,000 km and the Ecopia 110,000 km.

Also compare the price of Defenders vs Ecopia. I'm not sure but I think the Ecopia will be more expensive.

Lastly compare the performance of each tire. I can't find a direct comparison test between the two but my guess it's that the Defender will have better traction than the Ecopia.

If you look at the big picture it's likely the Defenders will be more economical and safer. Environmental impact will be hard to assess but you could make the argument of less waste with the Defender due to not replacing tires as often. Yes, you will lose bragging rights with your friends on MPG.

 

I am very happy with the Dunlop Enasave 01 A/S tires that came with my 2021 Prius Prime Limited Blue Magnetism. They are very energy-efficient and the handling is excellent. I've been consistently getting 77+ mpg in HV driving (84+ mpg before taking the ~ 4% drop in the SOC into account).

According to Consumer Reports, these are the tires with low rolling resistance:

Vredestein Quatrac 5 (62 points, performance all-season)
Kumho Solus TA11 (61 points)
Bridgestone Ecopia EP422 Plus (60 points)
Firestone Champion Fuel Fighter (58 points)

Michelin Defender T+H (67 points) is rated second only to General Altimax RT43 (T) (70 points) among all-season tires, but its rolling resistance is middling. General Altimax RT43 (T) has better rolling resistance.

I would have had the Dunlop Enasave 01 A/S OEM tires installed at a Toyota dealer if I were you. They are probably so–so-rated, but I like their razor-sharp handling and top fuel economy. You also get the peace of mind when you have the installation done at a Toyota dealer.

 

I'll add these comments, but doesn't really answer the question if you bought the wrong tires.
1) What is the treadwear rating as compared to your old tires?
Lower thread rating typically equals lower mileage, but reduced braking distance as one benefit of lower rating.
2) The "old" increase tire pressure trick.
Without a pyrometer, and assuming you have a "perfect" wheel alignment can be a bit of a guess until you are able to visually notice tire wear.
Bump up the current pressure by 3 psi and see if you like that.

Merry Christmas wishes to all our forum co-members.

 

This article discusses that non-low-rolling-resistance and/or low-profile tires are detrimental to the fuel economy and EV range.

Moral of the story: Always replace your Prius Prime's tires with the latest low-rolling-resistance OEM tires of the size and ratings specified on your tire placard.

Math proves big tire sidewalls are better for the planet

 

Noticed that on Google News; my take away: low-profile and low rolling resistance are at loggerheads.

We’re in the thick of that, with OEM 17” rims (around 24 lbs) and 215/45R17 all-seasons, vs 195/65R15 snow tires on 15” Corolla steel rims (maybe 16 lbs). The snows are neck-and-neck or better, for mpg.

 

2018 Prius 2, 2018 Prius 4 Touring.

I was able to do a side-by-side comparison of 15" vs 17", OEM Bridgestone Ecopia Plus tires.

After several months of ownership, it was very clear the 15"s delivered 58-62mpg, the 17"s 52-56. They never traveled identical routes, but in the exact same neighborhood, and similar driving styles (4 drivers sharing both cars)

 

You can sub 205/50R17, slight improvement I’d think. But they always seem to come in XL (extra load), which have (even) harsher ride.

By “ecopia plus” assume you mean “ecopia 422 plus”.

 

I believe the original post was about low rolling resistance vs "normal" tires. Size was never in question since it was always OEM (see post #5)

I agree smaller rims is the way to go unless you're really interested in looks. I had almost new winter tires on 16" steel rims from my old car that fit my new Prius. Tried them for a couple weeks on the Prius and ended up replacing them with the same tire but in 15" size on alloy rims. Car felt less sluggish and better MPG with the 15" rims.

 

Low rolling resistance can be a moving target: both our OEM Michelin Pilot HX MXM4 and replacement Michelin Primacy MXM4 were embossed with Michelin’s “Green-X” logo, their LLR designation.

The Pilots were pretty good, but when I swapped in the Primacy’s mpg TANKED. Two years later they’ve improved a bit. Bottom line: you need to take tire manufacturers’ LLR claims with scepticism, read owners’ reviews.

 

I would agree.

Moreover, the OEM 15" wheels will out-accelerate the 17" wheels - on the same model of tires - due to inertia / rotational-mass. I've tested this on bicycles, first, then much lighter - but same diameter as OEM (IIRC, 17", but 1.25" wider, instead of going with the 20" option) - wheels for my pickup truck. What I found was later tested and proven on the same model of truck at the drag-strips.

The only things low-profile tires are great for is for cornering hard - much harder than most Prius drivers ever take corners, and for their looks. Beyond that, if MPG or acceleration matter, the OEM 15" wheels are really tough to beat. (Low profile would also generally have a faster speed rating, but I haven't read of many - or any - folks taking off the 112 MPH speed limiter from their Gen4 Priuses.)

 

Yeah, the mass is closer to the middle (less centrifugal force), tread patch narrower, and overall weight less.

 

Living in Colorado, I use the stock ecopias and easily get 55ish on my AWD-e, but I switch to Michelin cross climates all seasons during winter and I get about 48ish. Michelin’s were never known for good economy and more meant for good braking and longer lasting tires (generally, not all models). Keep in mind that short trips will always get lower mpg performance than longer trips and you being an uber driving, you may want to reevaluate an alignment is needed which should improve mpg and typically a great time when you just got starting to break in new tires.

 

I swapped my Toyos for the defender and I also got a MPG drop as well in my 16 Prius. Expect about a 3-4 MPG permanent drop but the tires do seem to hold the road much better than the slick toyos in the rain.