Top 5 most fuel efficient tires (Lowest Rolling resistance: LRR)

[Ernie Rogers]

Originally Posted by Eddles

Feh. The £165 price for the EcoContact 3's doesn't include fitting - the website made me think so :/ It's actually £205.20 but it's still the cheapest than any other companies.

Now not sure if the EcoContacts are worth the extra £40!

My advice is if you have the money, get the tires. You will feel better, knowing you have done your best. But, check your fuel economy with the new tires, and if they don't prove out, take them back!

Ernie Rogers

[Eddles]

They don't have anything interesting in my car's wheel size, unfortunately.

Thanks for your advice though, much appreciated!

[Eddles]

Originally Posted by Ernie Rogers

My advice is if you have the money, get the tires. You will feel better, knowing you have done your best. But, check your fuel economy with the new tires, and if they don't prove out, take them back!

I agree. Thanks for your advice! I should see some difference as all 4 out of 5 tires on my car are of a different make.

Now to decide whether to keep the Michelin Energy Saver tire I've still got on the car or replace it with the EcoContacts, as the Energy Saver sidewall max pressure is only 44 PSI. That is, assuming the EcoContacts has a sidewall max pressure of 51 PSI

[jetta2.5L]

how do you i find this info out? kinda new to this....my tires are most likely the worst 205/55/16 continental contiprocontact RFT (runflats) i know they had about 5+/- ibs on th regular tires

[Eddles]

Find what info out? What's "ibs"? Sorry, not sure!

[Ernie Rogers]

Originally Posted by Eddles

I agree. Thanks for your advice! I should see some difference as all 4 out of 5 tires on my car are of a different make.

Now to decide whether to keep the Michelin Energy Saver tire I've still got on the car or replace it with the EcoContacts, as the Energy Saver sidewall max pressure is only 44 PSI. That is, assuming the EcoContacts has a sidewall max pressure of 51 PSI

I can tell you how it works for me. I put on four new, matched tires and leave any old thing for the spare--which is almost never used.

It's infuriating to me that the tire makers don't guarantee the rolling resistance of the tires. And, my response is that I hold them accountable if the tires don't measure up. I'm quite serious about returning tires if they don't give satisfaction. If you are up to measuring the rolling resistance coefficient of your tires, then that's what I would do. Otherwise, carefully track your mileage before and after you get them.

Some of us have mileage computers in our cars, like the ScanGuage. That makes comparing performance of tires much easier. If the new tires are a different diameter than the old ones, be sure to correct for that.

Ernie Roges

[CapriRacer]

Originally Posted by Ernie Rogers

I can tell you how it works for me. I put on four new, matched tires and leave any old thing for the spare--which is almost never used.

It's infuriating to me that the tire makers don't guarantee the rolling resistance of the tires. And, my response is that I hold them accountable if the tires don't measure up. I'm quite serious about returning tires if they don't give satisfaction. If you are up to measuring the rolling resistance coefficient of your tires, then that's what I would do. Otherwise, carefully track your mileage before and after you get them.

Some of us have mileage computers in our cars, like the ScanGuage. That makes comparing performance of tires much easier. If the new tires are a different diameter than the old ones, be sure to correct for that.

Ernie Roges

Ernie,

I am sure you are aware that new tires will have more RR than worn out tires - all other things being equal. I'm wondering how you account for that when you purchase new tires.

[Ernie Rogers]

Originally Posted by CapriRacer

Ernie,

I am sure you are aware that new tires will have more RR than worn out tires - all other things being equal. I'm wondering how you account for that when you purchase new tires.

Hmmm,

I KNOW I wrote a long reply to this question, but it's not posted. Hmmm.

My laziness is controlling tonight, so I won't reconstruct that reply--here's the short version. I'm not so sure that new tires are worse just because the tire is thicker through the tread area. I did a calculation and found that for my particular car, just the extra diameter of a new tire potentially raises fuel efficiency by about 2%. (Improves engine RPM.) And, I think a new tire loses less energy due to squirm because the deep tread allows more lateral flexibility.

I said to watch for a change in mpg with the new tires. I have an embarrassing story to tell--

I just got on a new set of tires last week. To save money, I went to a lower-quality tire--went from Michelin Energy MXV4 S8 (one of the very best) to a much cheaper tire, the Michelin Energy MXV4 Plus, apparently now on close-out by the factory.

Well, just watching my ScanGuage, it looks like my mileage has dropped by about 4 or 5 mpg, an 8% drop in fuel economy for my car.

I'm disgusted. I could take them back, but a set of S8s just isn't in my budget right now. Hmmm

Ernie Rogers

[Frank Lee]

I run them ol skinz til they blow; make sure spare and tools are on board. blowout = no biggie

[CapriRacer]

Originally Posted by Ernie Rogers

..........

I'm not so sure that new tires are worse just because the tire is thicker through the tread area.

.............

Anecdote:

You may be aware that I work as an engineer for a major tire manufacturer - who will remain nameless. Background to this story: At least one major vehicle manufacturer requires tire suppliers to monitor the RR of the tires being supplied - and that task is assigned to a QA engineer.

I was once asked to document all the changes made to a particular tire - and I ran across an entry where a new tread die was made to bring the tire back into RR compliance. I asked the QA engineer in charge what was with that - and he proudly whipped out a graph showing the RR by date and a gradual upward trend. He stated that the die used to extrude the tread component wears over time and gradually the tread gets heavier (and thicker). By making a new die, the tread was brought down in weight and the tread thickness decreased, and the RR was reduced.

BTW, the mold doesn't change so what would be measured as tread depth would not change. All the change in the volume of rubber in this anecdote is between the bottom of the groove and the top of the casing. This dimension is commonly called undertread.

Ergo: Change in tread rubber weight (volume) = Change in RR

I've encountered this principle in several studies of RR, but it's usually expressed as a "throw away / background" comment - as though this is so fundamental that it doesn't need validation. Perhaps it is because the studies that back this up are quite old and out of print.