2002 Toyota prius new tires worse mpg?

Question

I bought new tires for my car i bought the good year assurance same size i've had these tires before and loved them but i don't understand this at all... After i got them installed we went about 1500 miles down south i used to get about 48 mpg driving now i'm getting 30 to 35 thats a huge diff just for new tires the car does not shake or shimmy like a balance issue the tires are quiet and rides super quiet just getting very bad gas millige compared to the other tires any ideas??

Answer 1

US 2001-2003 NHW11 OE Prius tire:
Bridgestone Potenza RE92 XL (Extra Load)
P175/65 R14
84S
Treadwear 160
Temperature A
Traction A
50psi max. cold pressure

To my knowledge, these OE Bridgestone Potenza RE92 XL tires are LRR (low rolling resistance), so therefore you would see some increased fuel economy from them. However, they are not known for having a long tire life (as evidenced by that low treadwear rating of 160) - owners tend to report 20,000-30,000 miles average life on them (but I've heard of a few outliers at 8,000-45,000 miles on them). Proper inflation (minimum of the factory recommended pressure of 35psi front, 33psi rear) checked often, or slightly higher inflation (but still under the tire's max. cold pressure), is needed for long tire life. Improper alignment can also shorten tire life and lead to poor fuel economy.

It is really difficult to find a tire of the same size for the NHW11 Classic Toyota Prius like yours, and still maintain or better the load rating. To my knowledge, the Goodyear Assurance tires would have to be increased in size to keep the load rating.

New tires do require a small break-in period of about 500 miles or so to scrub off those little nubs and the tire-mould-separating chemicals, where the fuel economy will improve afterwards. If the new tires are heavier (weigh more) than the ones that you replaced, or if they have a larger footprint (either wider or improperly inflated too low), you can also lose some fuel efficiency.

I'd first check the inflation pressures on your new tires. I've never had a dealership properly inflate my Prius' tires (either they don't do the inflation at all (even though they check it off on the work order), or they put in the wrong (too low) pressures).

Do note that the temperatures have started to drop here in the Northern Hemisphere. Tires will drop pressure by about 1psi for every 10^F drop in outside temperature since they were filled, so your tires could probably use a top-up of air pressure anyways.

Did you have any other work done at the same time as the new tires? Overfilled oil and/or the wrong grade of oil is a common dealer problem and can also lead to lowered fuel economy.

Also, have you changed your climate control settings since the new tires were installed? With the colder weather, you may be using the heater more, which causes your gasoline engine to run more to provide you with "waste" heat. Did you forget the fan position in the front windshield position (front window defroster) - that'll run the AC compressor, which on your Prius is belt-driven off of the gasoline engine.

(Basically, how is this drop in fuel economy different than your same driving this time last year and the years before? Or has your driving pattern changed since the new tires (such as shorter trips)?)

Answer 2

The tires may be the same size only heavier than your old ones. However to me it sounds like another problem is present. It may just be that since getting the new tires your driving habits or normal driving conditions have changed. If you can't think of any reason for such a drastic change in fuel consumption, take the car to your local Toyota dealer. I can't offer much help for your car, considering it's a Prius.

Answer 3

The Toyota Prius averages 45-50 mpg in real-world driving. BETTER THAN EVERY GM HYBRID. The batteries don't have to be replaced for 100,000 miles or about ten years. If the battery goes out before that Toyota's warranty will cover it.

Answer 4

Yeah I changed tires on my Ranger and the mileage took a nose dive too. The manufacturer uses a real hard tire for longer life. Harder tire less rolling resistance, better mileage. The factory tires had better than 80,000 miles on them. Bit over 40,000 driven and a bit more than that towed behind my motorhome. That's how I know they were a real hard compound. Nothing else would have made it that far. Check your pressures and take a close look at your breather filter. A dirty filter can sneak up on you and it will really kill gas mileage. More so on FI vehicles than the old Carburated cars.

Answer 5

This doesn't make much sense. Make sure everything else is good, run a fuel system clear in the fuel tank. Check your tire pressure set them all at 35 -37 psi

Answer 6

the only thing that would cause it ,was if it was a lot larger tire,or smaller either one,there must have been something else that has happened to it,have the computer scanned and see if any trouble codes come up on it,i could understand it doing that if it had a much smaller tire or larger,but the same size,doesn't make sense,something had to have happened to it,good luck with it.