I tried to run a tank similar to what I ran a year ago to compare these new Energy Saver tires to the OEM Energy tires that came with my '07 TCH.

I figure about 55 mpg a year ago and I just filled the tank at 60.8 mpg. That's a 10% increase in mpg. Michelin says these tires can give up to a 8% increase. That would be 59.5 mpg using the 55 mpg as a base figure.

I looked back on my records and this time in 2007 I was getting 51 mpg. The jump to 55 was me learning more how to use the ev mode. It will take me all winter to figure my true percent increase in mpg with these new tires.

I did go ahead and add nitrogen to all 4 tires. I read that nitrogen can give you a 3% increase in gas mileage from poorly inflated tires.

Nitrogen resist leaking out. Some tires shops now replace with nitrogen for a charge. Costco and Sam's Clubs in many locations now use nitrogen only if you buy new tires from them.

http://www.saferidenitrogen.com/environment.html

Try your zip code below to find locations near you.

http://www.getnitrogen.org/

 

I assume they cost more, do you know how much more expensive they are than the 'on sale' tires available at Sears, etc? How many miles are they guaranteed for?

 

I'm a little skeptical of a 10% increase in fuel economy. If your previous tires were decent RR, you might see 5%. The Michelin Energy Saver is a very LRR tire though, by all reports.

Also, I wouldn't get too hung up on nitrogen. It's claim-to-fame is that it's less likely to escape from your tires. In practice regular air (which is 4/5 nitrogren, fwiw) doesn't escape much faster, and slow enough that it's a moot point if you keep on top of monitoring your tire pressures.

 

Just for the sake of argument, suppose that ALL of the gas that is not nitrogen will leak out of a tire in about a month after being filled. To keep the numbers round, suppose that we initially fill a tire with 40 psi of air, and that air is 80% nitrogen. (Air is actually 78% nitrogen.) After a month, the 20% that is not nitrogen leaks out. The pressure is then 32 psi. We refill with air. Then, the resulting mix is 96% nitrogen. (The initial 80% nitrogen, plus 80% of the added 20%.) During the second month, the 4% that is not nitrogen leaks out, and we refill again. Then the resulting mix is about 99% nitrogen.

If you want nitrogen in your tires, you can just fill with air and top-off a couple times after the pressure goes down. It costs a lot less than paying for the nitrogen. It costs me a lot less since I have an air compressor in my garage.

And no matter what gas you put in your tires, you still need to check the pressure regularly. Once a month or so is about right. Most people don't even check that often.

 

Jimmy, I have about 8,500 miles on mine now and I am seeing about a 4 to 5% increase above last years average. I'm very satisfied so far with these tires.

 

The Saver a/s tires cost about $150 each. That looks about the same as most top lines of other brands of tires.

I have no idea about Sears on sale tires. I'm thinking of something like a $89 tire.

I paid more for these tires due to their quiet, smooth ride, plus the much improved LLR feature. The utqg number looks like this may also be a long lasting tire.

Talking about more expensive, is like me asking, why pay $2000 more for the hybrid car over a regular Camry. My answer is a heavy car with a quiet, smooth ride that also gets good gas mileage.

 

Your right, it could be a simple 5% increase in mpg. It will take many months of driving to be sure. I wish I had these tires during the Spring so I could do a better comparison during the warmer months.

I was trying to repeat basically what I found on the two web sites about using nitrogen in tire. I did find that the Indy and nascar use nitrogen to prevent their tires from getting too hot.

 

Not to be a buzz-kill, but...
I applaud your efforts, the extra cost of the tires negates all of the savings associated with the tires fuel efficiency. In addition, it cuts into the savings you "earned" by your extra cautions driving style.
Now, I'm only commenting on the cost of the fuel.
Yes, you are performing an altruistic and environmentally friendly act, so for that, you should be proud, but in terms of dollars and sense, you would be better off with a pair of "what ever is on sale".
As to the quiet smooth ride, I have no idea what type of a difference there is, but as a life long buyer of non-premium tires (although, not necessarily the cheapest), I've never been bothered by the ride nor comfort of the tires I've purchased.
Again, I'm not trying to be difficult, but in terms of your wallet, the LRR tires are, on a net basis, more expensive than regular tires when factoring in the increased mileage.
You also mentioned the 'hybrid premium'. I've long argued that people, in general, will mainly pay it IF they saw a net break even or better on the fuel savings. Yeah, there are those that will buy it for the enviroment, etc. but I feel most will not pay too much for a hybrid if they'll never be able to recoup the cost in terms of fuel savings. Recent sales data of hybrids versus their gas equivalent proves this out (TCH sales declined at a higher rate the gas version).
===

My assumptions (assuming your stats).
I'll assume both sets of tires last 40,000 miles.
Regular tires 50 MPG, 40,000 miles=800 gallons
LRR tires boost mileage to 55 MPG (although some argue the savings are closer to 5%)=727 gallons
Saving 72 gallons @$3/gallon=$218 savings.
Tires cost ~$60 more*4 tires=$240 extra.
Net cost of LRR an increase of $22

Now, if the expected life of the tires varies from the 40,000 mark, the numbers change. In addition, it's possible that the LRR could last longer than regular tires, but also the opposite might be true. I don't know.

 

I remember well when Jimmy Carter removed the cap on gasoline prices. This was to help the oil companies search for new oil. Gas cost 50 cents per gallon back then and the next week I filled, it had shot up to 75 cents. I said to myself right then, I will do anything to get as high of gas mileage as possible. I started buying 4-cylinder cars which helped. In '94 I bought my first Corolla finding that toyota has a car that gets extremely good gas mileage. I remember I got between 36 and 39 mpg while driving it to work in Dallas.

 

(I know I've said this often, but...)
Over 35 years that's an increase of less than 5% per year.
If you look at the post OPEC spike (for example in 1979 gas was $1.25) that's a growth rate of ~2% to get to today's cost.
Coca Cola, water ($4 per liter at most professional sporting events), automobiles, rent, cable television and just about every product people buy today have shot up at significantly higher rates than the cost of gasoline.
In fact, compared to everything (except long distance telephony, computing and memory chips) gas is the cheapest commodity that we consume...by a long shot!

Remember when movie tickets were $1? They're now >$10.
Of course, back then you could see a double feature for that price.