New tires

Same initial problem here, but it takes time for the tires to "break in". I keep my tire pressure at 39/37 and change my air filter every 10,000 miles and I'm back to where I was (48 MPG with mostly70 MPH highway and some local driving) with my Infinities.

The ComforTreads are Great compared to the stock crap.

Enjoy!

 

I also replaced my Integrities with Comfortreds and immediately took a 5 MPG hit. I was able to swap the comforttreds for Regatta 2's. (I think they have a 30 day window when they will do that with no penalty as long as you swap for other Godyears.) The Regata 2's, while a LRR tire aren't much beter than the Comfortreds. In retrospect, I should have gone back to the Integrities. If I could swap for another brand, I would have gone for the Michelin MXV4's.

 

I had been looking arond for some replacement tires as my stock tires wore out on the edges.
I read through a lot of different tire reviews on the web as well as this board and decided to try a set of Pirelli P4 Seasons. Although in GA, where we have no rain anymore, I do travel North in the winter from time to time so I took that all into consideration.
Since I have had them on I have taken the 3-5 mile per gallon hit. Whereas I had say 44-46 just running around town, I am now hovering in the 41.8 range. This is with the AC on, in the 90 plus temps we have been having. Tire inflation is 42/40 and ride is better for sure with grip significantly better in water. (The one day it rained very hard I drove them around)
I have not had a chance to get them on a highway yet but the low mileage has me discouraged.

 

Greetings all,

I replaced my Integrities after 50K+ miles. Still had ~4/32" of tread on them but with winter coming thought that I shouldn't take a chance. The Integrities are fair at best in the rain and snow.

After much research, I decided on the Michelin Primacy MXV4 in the 185/65R15 stock size. The revs/mile are slightly less than the OEM tires. 851 vs. 855. That should help bring the indicated mpg closer to the actual and also the indicated mph as both of these seem to be slightly inflated.

I'm a person that uses "N" quite a bit so comparing the rolling resistance should be easy, right? Now that colder weather is here and the air is more dense influences how well the car coasts.

My initial impression (<300miles) is that these tires do not roll as freely as the Integrities but do seem to hold the road better in dry and wet conditions. Haven't tried them in the snow yet.

Does anybody have any input on the "breaking in" period for new tires? Is this a myth or is there actual data to support this theory? Would the fact that there is more rubber between the road and the car increase the rolling resistance? If we were running on solid steel tires the resistence would be minimal I would think. Think about a railroad car, steel wheels on a steel track. Not much resistence there but not much friction for stopping either.

Both sets of tires were and are run at 42/40 psi. The last tank with the Integrities was 52mpg, this tank is running about 47 so far. In the summer, I was routinly pounding out 60+mpg tanks, at this rate I think that 55 will be the most I'll be able to squeeze out.

This may sound great for some of you but consider whatever you are getting and take 8-10% off of it due to a tire change.

I consider part of it as the price I have to pay to have greater safety but it is a substantial hit. Maybe it will get better as time rolls on.

Kaos1

 

Good move, I do the same as winter approaches.

I first replaced my Integrities with Michelin MXV4+ "Energy Saving" tires (an older model - no longer available in 185/65HR15 size) and found that they got slightly better MPG (about 0.5 MPG) than the Goodyears, mostly due to better performance in the winter.

My current tires are Nokian WR all-weather tires which seem to be doing even better in MPG, but I need more data to get accurate results (5,500 miles so far).

The main "break in" factor is the steady increase in revs/mile as the tread wears. A secondary factor is as the tread wears there is less rubber to flex and therefore slightly less rolling resistance. The oft stated "break-in" effect may have been larger in the old bias ply tires as the reinforcing material took a set in initial use, but in modern radial tires, this is hard to see in the data.

I run the same PSI.

You can't rely on one tank (or even several tanks) to get a reliable MPG indication. I do a full year average (that's about 28,000 miles for me) before believing that I have reliable results.

That's a little pessimistic. Do your homework and find LRR tires. You should be able to do better than you did with the very poor Goodyear tires that come with the Prius. See 4 years of data attached as a zipped spreadsheet.

JeffD

 

I can't wait for the new Michelin Energy Saver to show up over here.

 

Your first 200 miles should be sufficient to break-in those new tires. If you just can't wait, peel some rubber and that should do it in an instant.