I just got new tires too. I didn't have any problem with my Dunlop SP31 OEM tires, I put about 64000 miles on them. I ran them at 42psi, had no unusual wear (except for slight inside wear due to the control arm issue). I was regularly getting 54-58 mpg. Since I was getting down to the wear bars, it was time to get new tires.
Because of the recommendations made here, I bought 4 new Michelin Pilot Exalto A/S 195/65R15 tires at Costco. They filled them to 43psi at my request (nitrogen). I decided to have my dealer perform repairs per Service Bulletin 08-001, new rear upper control arms and 4 wheel alignment.
I've run about 250 miles so far on this new setup and so far I'm extremely disappointed and distressed. I'm down to 46mpg which is nearly a 20% drop in mileage. The new tires are much quieter and smoother but I really didn't expect to take such a mpg hit. I understand there is a period of break-in with the new tires, but will I ever see my mpg get back to where it was (or better)? I'll post again with more info as I break these tires in. It's really frustrating to see my mpg go down, I hope this is just a temporary situation.

I'm wondering if I should have just stayed with the OEM tires...

 

Don't forget that ANY new tire will have more rubber (weight) than your worn down tire.

 

When I had the Pilot Exalto tires installed, my first tank of gas was down about 4 mpg, but after that the mileage then went up 3 mpg and then settled at about 7 mpg higher. I run these tires at 44 psi.

 

We had purchased Pilot Exalto AS for our 2007 HCH II under the 30 day total satisfaction guarantee from Michelin. I am a big Michelin fan and was excited to have these replace my Bridgestone SE200s that came stock. I had the control arm issue addressed about a week before installing the new tires and saw my MPG improve slightly on the SE200s after the change. Almost immediately after installing the new Michelins, our gas mileage dropped from the usual 44 we have averaged since owning the vehicle for over 18 months, to 33MPG. Nothing changed regarding how or where we were driving. Understanding that sometimes cars need to get used to their new shoes before they perform as normal, we ran the tires the full 30 days or almost 2000 miles to see if the MPG would improve. Much to our disappointment they did not.

We returned to where we purchased the tires and immediately went back to the SE200s, since we knew what mileage we were getting out of them before. As soon as driving home for the day from the office with the new shoes, our mileage returned to what it used to be, and in fact has improved a bit - I am guessing the control arms being replaced is improving things. We ran the Michelins and SE200 at 44 psi. One difference that was noted is that the Exaltos are 20 lbs according to the spec and the SE200s are 18 lbs, which I believe it what truly made up the difference, along with the LRR characteristics of the two.

In talking with numerous people about what they replaced their hybrid tires with, most have told me they stayed with the factory installed because they knew the mileage they would get. Many tire dealers are only installing what is OEM on Prius because that is what they know will not affect mileage. I am just glad I had the 30 day try and buy or I would have been dealing with a 30% hit to MPG!

 

If you had waited until the new tires settled in, you would have gone from a loss to about a 15% gain in MPG over your OEM tires.

Your experience is exactly what happened to me. The first tank had a big drop, then after 1-2K miles the average MPG jumped 15%.

Too bad you did not let the tires break-in. You would be seeing 48-49 mpg right now if you had stuck with the Michelins.

 

we actually ended up putting 2745 miles on the tires. I am not sure that our scenario is the same given you are on different rims and tire sizes than me, which can be a factor. I could not afford to risk the MUCH lower gas mileage. A 10-15% swing in gas mileage is understandable and likely one that could be made up from break in, but in order for me to improve on my previous mileage, we would need to improve 35+%, which I believe by any measure is a stretch for tires to improve on once broken in. I actually went off of your post as the recommendation originally, which I thank you for, but in the event it didn't work out, I didn't want to deal with having to sell the tires used, lose the MPG during that time, and then go through the hassle or removal and replacement at a later date.

 

I recently replaced my original Dunlops with the Michelin Exalto A/S (H-rated). These are the 195/65/HR15 size, same as factory. I've had them less than one tank, but notice very little difference in my MPG. It's probably 1-2 MPG less, but difficult to tell, really, on such a small sample.
Maybe the commute matters more for these tires. Mine is mostly highway, and a 35+ mile trek.
Or maybe you had the V-rated version of this tire. It could have different enough characteristics to affect mileage.

Orient Express, did you replace the Honda Civic EX's factory 16" tires on your car? I suspect THOSE tires were NOT the same LRR tires as are on the Hybrid from the factory (i.e., the Dunlop SP31 or the Bridgestone). I could EASILY see these Michelin's being better at LRR than the factory 16 inches.

 

Yes , my Hybrid does have 16" tires and rims. However, my average mpg on those tires was not been much different from those that have the 15" rims and do not hypermile.

My 16" Brigestones delivered mid-40s through their life, and the Michelin Pilot Exaltos deliver high 40s, low 50s.

 

Has anyone tried the Michelin Hydroedge? Michelin says they're the "The Most Fuel-Efficient Tire in the Category". Wet traction should be great, and that's one of the things people seem to dislike so much about the Dunlops.

Here are Michelin's recommendations for a 2007 Civic Hybrid:
http://www.michelinman.com/action/ti...on=Hybrid+4+Dr.

 

I put over 1000 miles on these new tires so far, just filled my tank this morning. I averaged 46.8 mpg for the tank, and that was really, REALLY trying hard. I think OE is correct, the Exalto's can deliver mpg's in the mid to high 40s, maybe low 50s are possible. However, this was my lowest mpg on a tank for over 2 years. I'm traveling 100+ less miles per tank, that's significant in my opinion. I don't think I'll be seeing mpg's in the high 50s or low 60s on these tires.

I'll probably be using the 30 day total satisfaction guarantee from Michelin and return them. I'm going back to the OEM Dunlops, I didn't think they were THAT bad, especially for the fair weather here in sunny Southern California . Part of my justification for having the HCH is to get as high mpg's as possible. I just didn't have to work so hard to hypermile with the Dunlops, and I was getting 55-58 mpg hardly trying.