2005 Prius: New Michelins--mileage took a nose dive!

[gawilson]

The Goodyear Integrity tires that came with my car had to be replaced at about 20,000 miles and a replacement set lasted about the same or less. I decided to go with Michelin Hydroedge based on long life but I never counted on losing 7-8 mpg in the process!
I'm told that this is the reason by the Toyota dealership but I truly question this. I wonder if something is going on in the hybrid system, i.e. electric motor failing to engage properly resulting in the gasoline engine doing most of the work or the battery not performing normally. Toyota won't check the battery or hybrid system at all unless a "light" is on in the dashboard. I also wonder if the number of miles requires a greater warmup time and thus more use of gasoline vs electric. I have also had the misfortune for a few wildlife "encounters"--deer hit me! I don't think that any of this would have adversely affected the aerodynamics but at this point I'm grasping at straws. I was getting 56-7 mpg's consistently on my drive to work and a bit better than that at times. It has dropped to 48-49 although I got 51 on my last tank.
Has anyone had a similar problem? It looks like when this happens all of a sudden, or in the case of a few folks that I've read on this blog where they're just not getting anything close to the manufactures ratings on mileage, that Toyota should double-check the hybrid system as well as the battery. Could they have this policy to insure that no battery problems are discovered before the warranty runs out?
greg
gawilson@tcia.net I'm on dialup-ugh, so if you have a definitive answer or suggestion, feel free to email me.

[ZC1]

Does the car have any alignment issues? Like pulling when driving or braking?
Did you change gas stations?
I wonder if the winter gas vs. the summer gas has anything to do with it?

ZC1

(of course, it could all be due to tire rolling resistance)

[brick]

New tires take a little while to wear-in, and mileage improves a little after that. But you don't say anything about tire pressure. How is yours set? You want those things nice and hard far the best mileage and longevity, with 42/40 or 44/42 being common recommendations around here.

The other thing that strikes me is that your integritys only lasted 20k. I know it's a lousy tire, but what happened to them? Mine have loads of life left at 27k, albeit having been inflated above 40psi since the beginning. If the edges rounded off, that is a symptom of having had too little pressure.

Please check pressures and get back to us. Best to take care of this now so that your new tires last!

[john1701a]

That's normal.

My new HydroEdges have 4,500 miles on them now. That new tread combined with unseasonably cold weather kept me from cracking 50 MPG until yesterday.

Break-In is a pain. But fortunately, you don't have to worry about it again for another 70,000 miles.

.

[JimboK]

Pretty much the same thing here when I put Hydroedges on last year. I estimated a 5-10% hit to fuel economy. I'm certain I've regained some of that now with 15K miles on the tires, but probably not all of it. The Integritys apparently are still somewhat lower in rolling resistance.

[donee]

Hi gawilson,

When you first got the car, your mileage increased the first 6 months you had it, I presume. Allot of that was engine break-in, but some was tire break-in. The tread edges wear down, and the sidewalls get more compliant. Take a new uninflated tire and flex the sidewalls. Then do the same thing with a worn out tire. You will notice quite a difference. That means, when each sidewall flexes the same amount, the worn out tire generates less heat in the rubber.

The Hydroedges make allot of noise when new. That is the factory siped (all those extra edges built into the tread). Over time the siping edges will feather in to the roll of the tire. And only come out to play when you put allot of force on the tread.

I am running Hydroedges, and they are 2 years old in June (about 24 K miles). My last suburban/combined driving tank was at 63 mpg. Summer traffic and construction helped allot with that though.

[VaPrius]

I put those same tires on my Prisu a couple months ago. I haven't noticed any mileage problems but my last set were almost bald. Plus the weather has been changing so frequently in my area any MPG hit has been due to that (I think).

[gawilson]

On the integrity tires, i just went with the manufacturers suggestions on tire pressure but on my Hydroedges, i run 42/40. My prius has about 75,000 miles on it and the hydroedges are well past break-in--i haven't noticed a real change yet. Weather does play a big role and i think that's due in no small part to air resistance overall, i.e. less humid is worse.
One person suggested that i check into the ethanol blend of the gas in my area and i'll do that--seems to be a good possibility. However, I still wonder about the overall hybrid system as the car ages, i.e. old cars run a bit colder than new cars and this could cause the gas engine to run a bit more to warm things up. I also wonder about how effectively the car is switching from gas to electric mode and whether the battery is performing up to par.
I think it's disgusting that Toyota won't check this without a warning dashboard light. Thanks for all the suggestions. Oh, it's been realigned several times in the past so I don't think that's an issue and even when it was out of alignment, the mileage didn't suffer--it was in the prior ranges I'd mentioned. Also, i did check out rolling resistance numbers prior to installation of the hydroedges and didn't notice that much difference. I notice it now though and it makes sense that it would be higher--this tire is guaranteed to last!
greg

[john1701a]

Originally Posted by gawilson

It has dropped to 48-49 although I got 51 on my last tank.

That's the basis of your complaint?

.

[F8L]

Originally Posted by gawilson

Also, i did check out rolling resistance numbers prior to installation of the hydroedges and didn't notice that much difference. I notice it now though and it makes sense that it would be higher--this tire is guaranteed to last!
greg

Where did you get RR #s for the Hydroedges?

I spoke to a customer care individual at Michelin yesterday and she said the Hydroedges are an efficient tire but they are not recomended for my area because of a lack of rain, it is a rain tire afterall. She said their most energy efficient tire is the Energy series tires like the Energy MXV4. It seems like she was just reading literature though so I am going to take her advice with a grain of salt.

Michelin on RR


What ever happened to the Proxima?