What size tires were on the car originally? What brand and model? What was their actual diameter and circumference? How much did they weigh?
What size tires are the Cooper CS4 88T tires that are now on the car? What is their actual diameter and circumference? How much do they weigh?
These are significant stats. Consider them, plus the differences in rolling resistance that may result from tire construction and tread design.
Yea higher rolling resistance of the new tyres, but also It’s Winter lower temperatures mean lower mileage.
You’re not the only one to take a mpg hit with new Coopers. I was getting a steady 23-24 mpg with my V6 AWD Mazda Tribute (I live in a rural area, lots of long distance highway miles)…now I struggle to get 21 mpg, stay driving. Some of the drop is attributable to colder temps. (we have 5+" of snow on the ground, and its 26 degrees right now), but I got the new tires back in September when it was still warm and noticed the dropoff immediately.
Consumer Reports rated the Cooper Discoverer H/T’s I had installed as below average in rolling resistance. I blew that off, thinking it might steal .5 mpg at the most. Well, it was a lot more than that.
The original tires were a really crappy set of Continental ContiTracs. They were the loudest set off tires I’ve ever heard. I wonder if Mazda and Ford picked those tires for the low rolling resistance to get inflated gas mileage numbers in EPA estimates???
I put new Michelins on my Prius during the autumn weather. It never gets that cold here, and we have no snow. My mileage has gone down between 8 and 10 mpg. All I can figure is that it is the tires. The Tire man says “it ain’t so.”
EPA mpg ratings in 1981 were very optomistic (the cars couldn’t get what was advertised)this rating system produced such inflated mpg figures that the method of testing has been revised to be more in tune with reality.
In your case we have a car that exceeds these inflated figures.
What I am commenting on is the concept of these extreme high mileage cars from the 80’s and the question of “where are they now” Myself, I feel its a case of “foggy memory”
Wow. This thread is from 3 months ago. Can’t we just leave the old ones alone?
I have no idea why I missed this thread the first time, but I did and since it has been resusitated:
New tires have higher rolling resistance than worn out tires - all other things being equal. Put another way, even replacing tires with EXACTLY the same size / manufacturer / model is going to result in loss of fuel economy.
As was pointed, Original Equipment tires generally have lower RR than tires designed strictly for the replacement market. This is one of the reasons why many people complain about the traction or the wear of the tires that come on their new car - the vehicle manufacturer specified a low RR and that results in poorer traction or wear (or both).
And in this case, Hybrids are generally equipped with tires that are even lower in RR.
So the OP took 3 hits in the fuel economy department.
But I wonder what the numbers in the OP were about? “(48/49 to 43/44)” Inflation pressure? If so, then this is another reason.
I just googled ‘Prius gas mileage cooper tires’ because I have lost 4 mpg on my '07 Prius since buying Cooper tires at Pep Boys. Big mistake I guess. I took it into dealer, and after they said they could find nothing wrong with the car, they noticed my new tires and said Cooper tires aren’t among the four brands recommended by Prius. I plan to try to make Pep Boys take them back. The tank refill light is going on at a lower mileage so I don’t think the bigger tire thing deals with the issue.