Best truck tire for MPG?

[Hokiefyd]

Originally Posted By: Char Baby
I have a head cold this week and I'm not thinking straight(or did I miss something) but, what is LRR?


Low Rolling Resistance. It's not (yet) a consistently-recognized characteristic of a tire, but it's getting there. Tire Rack, for instance, now does indicate whether the manufacturer classifies the tire as a LRR tire, on the spec page for the tire.

As I understand, there are SAE test protocols that define consistent procedures to measure a tire's rolling resistance. I look forward to the day when manufacturers offer up that data just like they do weight and revs/mile, etc.

 

[mshu7]

One other thing to think about when considering the MPG side of tires is the tire WEIGHT!. In the past I unknowingly put tires on a car that were 4 lbs. heavier than what was on there before (according to the data on Tire Rack). That 4 lbs. per tire made a HUGE difference in the performance of the vehicle as well as the gas mileage.

Something to think about...

 

[CharBaby]

Originally Posted By: Jimmy9190
LRR = Low Rolling Resistance


I should have known!

 

[Jimmy9190]

As good a deal as the DT $70.00 rebate and sale price on LTX M/S2 is, I think I will wait and see if any good after-Christmas/New Year's sales or rebates come along. I don't like the feeling of being in a hurry to beat the deadline for the sale and rebate, and I sure don't feel good about giving out my debit card info over the phone. I took a real good look at my tires today, they should last me at least until May or June with no problems. If a good deal on a sale price and/or rebate comes along between now and then, I may go for it sooner rather than later.

Thanks everybody for the help here. There are so many choices and prices on tires it is hard to know which one to buy and which tire is best for the price you pay. I do have some time to wait it out for a good deal. My Destination LE's have been very good tires for what I paid for them, and they are still in good shape now at 41K even if they are a bit loud now. The degree of tire noise varies with the type of road surface too, some roads are not so bad as others. But it's not like I'm riding on Unsafe Maypops and need new tires yesterday.

 

[CapriRacer]

Originally Posted By: Hokiefyd
Low Rolling Resistance. It's not (yet) a consistently-recognized characteristic of a tire, but it's getting there. Tire Rack, for instance, now does indicate whether the manufacturer classifies the tire as a LRR tire, on the spec page for the tire.

As I understand, there are SAE test protocols that define consistent procedures to measure a tire's rolling resistance. I look forward to the day when manufacturers offer up that data just like they do weight and revs/mile, etc.


First, while there are various SAE tests, the end result of each of the tests is a DIFFERENT number - and while these test correlate very well, there has to be an agreement as to what is going to be published.

The Good News: The federal government has stepped in - in the form of NHTSA - and proposed a change to the required UTQG ratings of tires that would include fuel economy as part of the rating. To this end they ran correlations between all the possible tests and proposed a single point test, which would be easy to run.

They also ran correlations between test facilities and they developed a way to get consistent and reproducible results.

Bad News: The bureaucrats have decided that they want to use Rolling Resistance Force (RRF) as the published value - saying that it would make tires for SUV's and pickups look terrible compared to tires for microcars. They think that would encourage people to buy smaller, more fuel efficient vehicles.

The tire industry has objected. They want to use Rolling Resistance Coefficient (RRC = RRF divided by the test load). This makes larger tires appear more efficient than smaller tires. They say that this is the way people buy tires - and that using RRF would tend to reinforce the mistaken belief that smaller tires are better - and this is the wrong direction for safety (ala the Firestone situation a few years ago).

Also, the proposed rule would have required every size/design combination to be tested. If I remember correctly, that would take over 3 years to accomplish utilizing EVERY test facility in the world - and of, course, any testing for research would add more to that figure.

A hearing with the GSA was held in October of 2009, and a ruling was expected in February, 2010. The ruling never was issued as NHTSA went back to the drawing board. I suspect they were told by the GSA that if they didn't rethink the thing, the GSA would rule in favor of the tire industry - and that would result in RRC being mandated.

- and that's where it stands.

I can't speak for other tire manufacturers, but the company I work for has started doing the testing in order to shorten the process. Their plan is to test samples to get a feel for where a particular tire line stands. That would allow them to predict each size/design combination. Then follow that up with filling in the gaps. As new tires are developed, predicting the final design's RR is part of the development process. I suspect other tire mnaufacturers are doing the same thing.

 

[CharBaby]

Wise choice! This give you time to make an educated decision based on your driving style and climate.

 

[Hokiefyd]

Originally Posted By: CapriRacer
- and that's where it stands.


Thank you for the update on this topic! I know it was debated earlier this year, and I understood what you reported: that in the end, all parties went back, almost to square one, to rethink the whole thing.

 

[mshu7]

Originally Posted By: mshu7
One other thing to think about when considering the MPG side of tires is the TIRE WEIGHT! In the past I unknowingly put tires on a car that were 4 lbs. heavier than what was on there before (according to the data on Tire Rack). That 4 lbs. per tire made a HUGE difference in the performance of the vehicle as well as the gas mileage.

Something to think about...


Just wanted to reiterate this.

 

[mshu7]

Just stumbled upon this Tire Rack article about price vs. value.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=75

 

[CapriRacer]

Originally Posted By: mshu7
Originally Posted By: mshu7
One other thing to think about when considering the MPG side of tires is the tire weight. In the past I unknowingly put tires on a car that were 4 lbs. heavier than what was on there before (according to the data on Tire Rack). That 4 lbs. per tire made a HUGE difference in the performance of the vehicle as well as the gas mileage.

Something to think about...


Just wanted to reiterate this.


To add some depth - see page 24:

http://www.energy.ca.gov/transportation/...e%20Testing.pdf

That says there is only a 20% correlation between tire weight and rolling resistance for tires of the same size. Put another way, only 20% of the difference in rolling resistance between tires can be explained by differences in weight. That's not very good.

On the other hand, that was the best correlation they got. Obviously there is a lot going on - some of which may be hard to identify.

 

[Loobed]

Originally Posted By: mshu7


Being the owner of an 04 Colorado Z71, I can tell you that the tires you are probably referring to are General AmeriTrac TR's. I have found that most OEM tires are junk, so it would make sense that you did not like the AmeriTrac's.



The poor wheel alignment on Chevy/GMC trucks doesn't help the tire last very long either. Most OEM truck tires are rated to about 40K miles.

 

[mshu7]

Originally Posted By: Loobed
Originally Posted By: mshu7


Being the owner of an 04 Colorado Z71, I can tell you that the tires you are probably referring to are General AmeriTrac TR's. I have found that most OEM tires are junk, so it would make sense that you did not like the AmeriTrac's.



The poor wheel alignment on Chevy/GMC trucks doesn't help the tire last very long either. Most OEM truck tires are rated to about 40K miles.




You're not kidding. Speaking of which, is it just an alignment issue or something more than that? The inner shoulders of my current tires are shot.

 

[CapriRacer]

Originally Posted By: mshu7
......is it just an alignment issue or something more than that? The inner shoulders of my current tires are shot.


It's the alignment. Anytime one side of the tire wears more than the other side, the tire is not being aligned properly to the road. Many folks will point to the "Alignment Specs" and say "It's in spec!", but the alignment specs themselves could not be set up for good tire wear.

A good example are BMW's where they "spec" quite a bit of camber. This causes the tire to be at an angle to the road. While this really helps cornering, it also causes the inner shoulders to wear more rapidly than the outer shoulders.

There is also a thing called "akerman". When you turn the steering wheel, the steering tires do not turn the same amount. In other words, they don't wind up pointed in the same direction - and they shouldn't. The outer tires have to traverse a larger diameter circle, so the inner tires have to be pointed more towards the center.

To complicate matters, in order to produce the forces necessary to turn the vehicle, the tires have to develop a slip angle - a difference between the direction the tire is pointed vs where it is actually going. This is a complex relationship and sometimes the car designers don't quite get it right. (To be far, the relationship involves loads, pressures, and speed, so it is somewhat understandable that they might miss it once in a while.)

Further, there is a combination of turning radius and speed for each amount of akerman, so if a car is set up for a larger diameter turn at high speed, taking sharp corners results in a different amount of akerman needed. In other words, one of the tires is dragged through the corner. You can sometimes hear this when the tires squeal when a car is parked in a parking deck with smooth floors.

 

[mshu7]

Originally Posted By: CapriRacer
Originally Posted By: mshu7
......is it just an alignment issue or something more than that? The inner shoulders of my current tires are shot.


It's the alignment. Anytime one side of the tire wears more than the other side, the tire is not being aligned properly to the road. Many folks will point to the "Alignment Specs" and say "It's in spec!", but the alignment specs themselves could not be set up for good tire wear.

A good example are BMW's where they "spec" quite a bit of camber. This causes the tire to be at an angle to the road. While this really helps cornering, it also causes the inner shoulders to wear more rapidly than the outer shoulders.

There is also a thing called "akerman". When you turn the steering wheel, the steering tires do not turn the same amount. In other words, they don't wind up pointed in the same direction - and they shouldn't. The outer tires have to traverse a larger diameter circle, so the inner tires have to be pointed more towards the center.

To complicate matters, in order to produce the forces necessary to turn the vehicle, the tires have to develop a slip angle - a difference between the direction the tire is pointed vs where it is actually going. This is a complex relationship and sometimes the car designers don't quite get it right. (To be far, the relationship involves loads, pressures, and speed, so it is somewhat understandable that they might miss it once in a while.)

Further, there is a combination of turning radius and speed for each amount of akerman, so if a car is set up for a larger diameter turn at high speed, taking sharp corners results in a different amount of akerman needed. In other words, one of the tires is dragged through the corner. You can sometimes hear this when the tires squeal when a car is parked in a parking deck with smooth floors.


You sure know your steering/suspension!

Ok, so even if they put everything to "factory spec" and it's off, can I just request the shop to align it to a spec that isn't going to wear out the inner shoulders?

I knew alignment was part of the issue, I just wasn't sure if it was the only issue. Sometime in 2011, I'll be replacing the shocks and put on bigger wheels and tires. I just needed to know if I was looking at other issues outside of an alignment before dumping this money into the truck.