My dilemma: handling vs fuel economy

[ueberooo]

I currently have a set of tires on that need replacing because of a slow leak that cannot be fixed (plus, another tire is worn such that the set has about just 1 year left anyways). The 60 profile is why I think they seem to handle so well:

205 60 r15

They stick like glue on curves and are absolutely great handling-wise.

My idea is to replace them with more economical tires; slightly narrower and a higher 65 profile:

195 65 r 15

They have a slightly larger diameter (1.2%: 807 versus 817 revs/mi) and are slightly narrower (5%).

I have verified with a vacuum gauge that the engine would benefit (efficiency wise) from revving lower on the freeway (used a manifold vacuum gauge).

My only concern is that the economy gains will be insignificant while the handling may not be as good (since the profile is increasing 8% from 60 to 65.

Fuel economy is my main reason for wanting to switch, but another reason is also that narrower tires generally have some advantages in snow over tires that are too wide (The road pressure on the narrower tires will be a little over 5% higher.)

Any guess as to which might be the better choice? or better yet, guestimates for % mpg increase vs % loss in lateral acceleration?

My wild guess is that I will get up to a 1% mpg mileage improvement, and I have no idea as for a guess regarding the handling--other than having tried a 185 75 r14 profile set of tires that had decent handling but was very noticeably not as great as those of the 60 profile.

 

[OldCowboy]

It's pretty obvious that you really like the handling of the 60 series tire. I would stay with that. Your mileage gains with the 65 series will be modest, at best, as would the snow traction.

The best situation would be to have a summer set for handling and a winter set for snow traction.

 

[ueberooo]

Originally Posted By: OldCowboy
It's pretty obvious that you really like the handling of the 60 series tire. I would stay with that.


How much do you think it would affect the handling (going from 60 to 65 and a tad narrower)??

I'm just wondering if it'd be as insignificant as the fuel savings.

(I think I would be lucky to save 3 gallons of gas a year... which when I think about it for a while isn't that much.)

I like good cornering but love experimenting too, so this is still a hard call for me!

 

[kr_bitog]

It depends how fast you corner, however, IMO, for Subie, 205 is the better compared to 195, that may not give enough traction during high speed cornering due Subie can hit more than 120mph easy. For lighter car, 195 may be the best due to wet traction, but Subie is not that light, so 205 will not suffer much on aquaplanning. Furthermore, 65 series will not have good option of performance tyre.

For snow traction, definitely dedicated winter tyre will be the best. When you start consider all-season, you will just left not here and not there in term of performance.

 

[Smoky14]

Michelin Primacy MXV4 series, get both

 

[AstroTurf]

Have a look at the Nokian eNTYRE tire.

It may give you the best of both worlds.

Jim

 

[Garak]

Originally Posted By: ueberooo
I'm just wondering if it'd be as insignificant as the fuel savings.


I agree that this decision is a hard call. The average person never takes his tires to the limits anyhow, so something with "lesser" handling isn't an issue for them.

The only thing I can really add here is to address the general economy situation. Which is cheaper? A 195/65 may have longer treadwear, too, if that's an issue for you.

Of course, if cost isn't an option, the suggestion of going for separate summer and winter tires is the best one. I don't much like monkeying around with tire sizes, so that would be my preferred option, albeit a more expensive one.

 

[CapriRacer]

In order to answer your question, I need to bring you up to speed on the technology.

1) Fuel Economy, Treadwear, and Traction are a 3 way compromise when it comes to tread compound. Put another way, if you want improvements in one area, one or more of the other areas has to be sacrificed.

2) There is a HUGE!!! range of values for these 3 properties within a given tire size.

3) All other things being equal, a larger tire (as measured by the load carrying capacity - use Load Index) will be better for rolling resistance. However, the difference between tires of slightly different size is small by comparison to #2.

4) Handling - meaning the feel you get - is balanced against ride quality - think ride softness. These are opposing properties.

5) Going to a larger tire can result in an improvement in handling without the loss of ride quality - or - an improvement in ride quality without a loss in handling.

Assuming you are using the terms as above, then you can get BOTH good fuel economy and handling in the same tire.

Further, the 2 tire sizes you mentioned are not exactly equivalent - and the 195 will actually result in a loss in fuel economy from the rolling resistnce point of view. There may be some small improvement due to the larger diameter, but I think it is a wash!

My advice would be to go to a 205/65R15 and select a tire with good handling ratings in the surveys - being aware that the average consumer doesn't use the word "handling" consistently. Also be aware that you have to be careful to select a tire with good fuel economy as well.

You can completely screw this up if you aren't careful!

 

[Michael_P]

Speaking of cornering, the faster you go on lets say a cloverleaf exit, the less you have to slow down and re accelerate, reducing downshifts and what not. When I drive our third car which is a 2001 Mazda Protege MP3, I take cloverleafs faster than most. I always beat the EPA estimates for this car. It has very sticky tires. Part of hypermiling involves not going as fast but also involves not slowing down as much on the curves. Just thought I would add a useless dimension to the thread. If you do not speed a better handling tire hardly takes a a mileage hit. Though as you drive faster, resistance increases progressively with high performance tires.

 

[JHZR2]

take a look at bridgestone, the seem to have lots of LRR tires in various sizes.

 

[oldmaninsc]

Originally Posted By: ueberooo


My wild guess is that I will get up to a 1% mpg mileage improvement . . .

You do understand that 1 percent is basically insignificant? Let's say for the sake of argument you normally get 20 MPG. A one percent increase means you will get 20.2 MPG. In my opinion not enough to even discuss. If you drive 200 miles a week, the .2 MPG increase will save you about 35 cents a week.

I think CapriRacer gave you some very good advice. Personally when I pick a tire I like to find a smooth ride first, then handling, then MPG. I don't drive at break neck speeds around turns so handling isn't as important to me.

 

[GMBoy]

I choose safety and handling over fuel economy, escpecially as small a gain that it "might" save you. I agree with the guys suggesting a low rolling resistance tire in the same size as an option. I never liked going smaller in tires.

 

[4x4chevydude]

I would say stay with the same size tire and go to one of the ECO ones they have now...Bridgestone Ecopia 422 are good tires and low rolling resistance so you get better MPG. Michellin and Goodyear also have versions of these as well.

 

[JOD]

Capri Racer is spot on; the construction of the tire is what really makes the difference, much more than the size. "All else equal", wider tires roll better, but it's tough to keep all else equal and have the tires fit in your car.

That said, I'd stick with the 205/60's and pick a tire that rolls well. The difference between the best and worst tires is a lot more than 1%--it can be up to 5% or more, so it's not insignificant. I'd check out these tires:

http://www.michelinman.com/tire-selector/name/energy-saver-a-s-tires?Wt.mc_id=Paid%20Search;Google;michelin%20energy%20saver%20a/s&WT.srch=1

 

[mechtech2]

That 1.2% is small!
Actual results will be modified from things like rolling resistance inherent in any tire due to tread design and compound, tire pressure, alignment, and frontal surface area [wind resistance].
The new tire size probably won't feel as 'slot car' like as the old ones in immediate response and transients.
But if you really want the handling, get the 205s and run the pressure 3-5 pounds over the door sticker for best gas mileage.

 

[Carbon]

You will not see fuel economy contest winners running wide tires. You will not see solar powered car winners running wide tires. You will not see human powered vehicle racers running wide tires.

 

[HTSS_TR]

I think either 205/65-15 or 215/60-15 will be better than 195/65-15.

 

[GMBoy]

Originally Posted By: Carbon
You will not see fuel economy contest winners running wide tires. You will not see solar powered car winners running wide tires. You will not see human powered vehicle racers running wide tires.

Maybe so, but those are super skinny tires, not what we want on cars and the tiny difference in size the poster was referring to is simply not worth it.

 

[CapriRacer]

Originally Posted By: Carbon
You will not see fuel economy contest winners running wide tires. You will not see solar powered car winners running wide tires. You will not see human powered vehicle racers running wide tires.......


Just an FYI for those who don't know. Carbon and I had a disagreement about larger tires having better rolling resistance.

Here's my take on the subject:

http://www.barrystiretech.com/rrandfe2.html

 

[Carbon]

Originally Posted By: CapriRacer

Just an FYI for those who don't know. Carbon and I had a disagreement about larger tires having better rolling resistance.


CapriRacer is very expert on tires, and we are fortunate that he shares his very useful and interesting knowledge. My thinking is that on this very limited point-- whether larger tires on the same vehicle will give lower rolling resistance-- he has over-inferred a conclusion.