Two days ago, I got Cooper CS4 tires to replace OEM on my 2011 Prius Three. Leaving the dealership my mpg went down to low 30's, about 35mpg. Prior to that I was getting 54-56mpg! Two days later, I'm still getting 32-33-35mpg around town. Called Toyota dealership and they said they'll take a look at it but that doesn't seem normal. I know it's not normal, jeez. What gives. Nothing is on, not the brake, not the ECO mode, not the power mode, so can tires cause such an enormous drop? No way am I driving a Prius that gets 30'smpg.
Are those Cooper tires LRR? Also, check the tire pressure to make sure it's at 40 psi when the tires are cool
Check the visual alignment of the wheels. Do they generally seem straight? They could have got knocked out of alignment by a sloppy mechanic. I'd put the steering wheel straight and see where the wheels are pointing. Do you know if they rebalanced the wheels when they put the tires on?
Can having non-LRR tires make the much of a difference? My new-to-me Prius has Pepboys Futura HR Touring tires and I am getting 50 MPG.
CooperTiresConsumer - CS4 Touring (T Rated)<span class='trademark'>™</span> Does not mention LRR, does mention 45 day test drive, so maybe they take them back, and you get Michelin Energy Saver A/S
JimboPalmer, thanks for the link! and the advice. Not LRR, but shouldn't be such a major drop, I wouldn't think. Alignment is good as far as eyes can tell. They did an alignment and balanced tires. Can't check pressure bc gage cannot be located at the moment. I'll update Monday after they check it out.
I would expect a 5% drop with any new tire, as the diameter changes. 5% for LRR would not be impossible. After that, I am unsure where the MPG is going.
A big time YES. I had some fitted in error and my mpg's bombed. I'll always use LLR tyres in future. Worth the extra money, esp here with petrol over $8 a US gallon.
I would recommend that you check tire pressures & get a tire alignment. They should be at a least 40psi (Front) and 38psi (Rear). I personally never trust the people at tire shops or dealerships to check my tire pressure, there are too many inconsistencies! Always check your cold tire pressure at least every 2 weeks or once a month (minimum), with a good tire pressure gauge.
Update: I switched the Coopers with the Michelin Defender LLR. I consistently stayed in the 40mpg range with the Coopers. My mpg was at 42 the first day after switching, 47 the second and third, and by the end of the week, I'm sitting pretty up at 56-57, much better than pre-tire replacement!
This is a bizarre story. Does anyone have any plausible explanations? There is no way tires themselves would create so much resistance. Don't tires account for only 7% of energy loses?
Nope, no plausible explanation. No one can figure it out. I'm just glad it's all over; it was like an awful nightmare come true - kinda like sitting in a Starbucks drive-thru and wrecking your car I paid an extra $25 per tire and another mount & glance fee equaling another $160 but I don't care. I will never try a non-LLR tire again.
Well crap, didnt know about lrr tir Goodrich Advantage T/A tires on it which I dont beleive are LRR tires..... Guess Ill see how well or crappy these things do. If I had known i would have tired to negotiate LRR tires into the deal..
I meant to say I just bought my car from the dealer and those are the tires it had on it in above post, they are brand new though so Dont really wanna pay for new ones already....
Non LRR tires will kill your MPG. The weight alone will make a huge difference. I took my stock 175/65/15 GY tires off and put on a set of new rims with new 195/65/15 Michelin Hydro Edge tires off my Civic. My MPG data showed the same as the OP's. After my new Kumho EcoWing 185/65/15 tires came in, it came right back up to normal. The Michelin tires added almost 10 lbs per wheel compared to the stock tires and wheels. Weight is as much a factor as LRR
I do not know, maybe selling these off on craigslist and getting new ones. But then Ill have to get alignment and all. Not gonna be cheap at all
