Choosing a Tire
 

I have 175/70/13 on my corolla right now, Michilen Radial X, from Costco.
I just found out the stock size is 155/80/13.
I guess finding tires in my oem size are harder.
So comparing the two here is what I found out.

I currently have 175/70/13 size "Radial X" on it right now came with the car.
Section Width: 7" on 5" rim
Rim Diameter: 13 in 330.2 mm
Overall Diameter: 22.68
Sidewall Height: 4.82 in 122.42 mm
Radius: 11.32 in 287.52 mm
Circumference: 71.12 in 1806.4 mm
Revs per Mile: 917

I just found out 155/80/13 is the OEM size for my 90 Corolla Coupe.
Section Width: 6.10 in 155 mm
Rim Diameter: 13 in 330.2 mm
Overall Diameter: 22.76 in 578.10 mm
Sidewall Height: 4.88 in 123.95 mm
Radius: 11.38 in 289.05 mm
Circumference: 71.50 in 1816.1 mm
Revs per Mile: 913.8

Of course with slight variances for different tire brands.
(Basically my 175/70/13 tire is .536% to fast & Diameter Difference is 0.53% to small)
That is about 5 more revolutions of the tires/wheels for 1 mile on the car currently. The width is 6.88"in compared to the stock 6.10"in width. I can save about .78" or 3/4" on my tire width. I guess getting the stock size tires will improve my MPG and resistance/drag a little bit so I will be putting the OEM recommended tires back on these wheels.
My problem now is finding a 155/80/13 tire for more MPG or energy saving tires.
I just went to tirerack and found only 2 (two) tires they sell for my size:mad:
Are my tires so small and out of date or is it the small size is a good benefit already that is does not have to be mentioned? Either way Here is the comparison of the 2 i found in my OEM size. I never through downgrading tire size would happen to me.
They are:
Kumho - Solus KR21
http://www.tirerack.com/images/tires...21bw_ci2_l.jpg
Section Width: 6.2"in
Overall Diameter: 22.8"in
Weight: 14lbs
Tread Width: Not Listed
Revs per Mile: 914
Made in China?? Humm
$200 per set
-or-
Firestone - Winterforce
http://www.tirerack.com/images/tires...orce_ci2_l.jpg
Section Width: 6.2"in
Overall Diameter: 22.8"in
Tread Width: 4.6"in
Weight: 16lbs
Revs per Mile: 910
Made in Argentina?????? WHAT! lol
$196 per set

Weight savings and closest to OEM is the Kumho Solus KR21 for $200 a set.
Not bad and a total of 8 lbs lighter for a full set then the Firestone tires, I do not have a very good picture of them anyways. I guess Korea is getting my dollar but the tires are made in CHINA?!? I guess labor is still cheaper in China then in Korea and will probably stay that way forever due to the overpopulation of china and the vast size of its land. They are both comparable in all surveys but it seems the Firestones ranked better and supposedly get better dry traction?
From all the reviews of people on both tires it seems the Kumho's are getting 3 to 4 times the distance out of them and only cost $1 buck more each. I knew Firestones sucked:D Plus I am not putting winter tread tires on my car, the sound would be horrible by looking at the tread pattern. Where else can I find tires in my size sheesh!
Anybody have any opinions I would love to hear them.

I also looked up a 185/60/14" tire which is only a .09% to fast which is pretty good but that would mean I would have to find a 1" larger wheel set which might add more weight and no Resistance saving tires in those sizes.
Also they do not sell any ECO - Energy Saving or Low Resistance tire in those sizes.

They do make two decent Low/Eco Rolling Resistance tires in my current 175/70/13 size which is the:
eco Solus HM KR22
Section Width: 7.1"in
Overall Diameter: 22.6"in
Tread Width: 5.8"in
Weight: 16lbs
Revs per Mile: 919
$228 per set


And the Michelin Harmony
Section Width: 7"in
Overall Diameter: 22.5"in
Tread Width: NA
Weight: 16lbs
Revs per Mile: 923
Cost $308 per set

People do seem to be getting around 30-50k miles out of the Michelin compared to the Kumho tires in this size.

I don't know if this tire would get any better MPG then the smaller stock size& I would not like the difference in my spedo either.

Would possibly getting a taller tire then stock raise my MPG? I have not looked into it.

Where have you seen the Michelins rated as an eco tire? I have not seen that. I have only seen the eco solus described that way this this size category.

Maybe I didn't mention low rolling resistance, but I just figured tires with low rolling resistance are eco tires since they save gas but is there a difference in a eco tire? Is it made organically or from renewable/recycled materials or am I missing something here? Or I think it;s just a combination of everything making it "greener" right?
Well rated as a low rolling resistance tire but I just found it on consumer reports and here it is: and since low rolling resistance is also contributes to less rubber on the road I would be looking for the stiffest skinniest contact patch i guess. None of the tires below were made in the OEM 155/80/13 size which sucks.

Also**
A tire Labled "ECO" was just one that passed tests with the "Green Seal", a non-profit, third-party certifier and standards development body in the United States.[1] Since 1989 it has provided independent, objective, science-based guidance to the marketplace and to consumers. Green Seal is the largest[citation needed] US-based ecolabeling organization and meets the United States Environmental Protection Agency's Criteria for Third Party Certifiers, the requirements of ISO 14020 and 14024, and the standards of the Global Ecolabelling Network. Green Seal is the U.S. member of GEN which consists of 26 of the world's leading ecolabeling programs, including Germany's Blue Angel (certification) and the Nordic swan.

Maybe they did not test all the tires out there. but just tires in a certain general size.
"
Here is a list of Consumer Report's tires that achieved their best rolling resistance rating. The tires at the top of the list are rated higher overall.

Highly rated:
All Season
Michelin X Radial
Michelin Agility Touring
Michelin Harmony
Toyo 800 Ultra
Sumitomo HTR T4
Middle rank
Performance All Season
Michelin Energy MXV4 Plus
Continental ContiPremierContact H

Least benefit
All Season Ultra High Performance
General Exclaim UHP
Continental ContiExtremeContact
Below are the light duty tires (as reported by Consumer reports) achieving their best rolling resistance rating. Again, higher overall rated tires are closer to the top of the list.

All-season
Bridgestone Dueler H/T D684
Michelin Cross Terrain
Continental ContiTrac SUV
BFGoodrich Radial Long Trail T/A
Followed by:

All-terrain
Continental ContiTrac TR
New models by 2009:

Michelin Energy Saver
Goodyear Assurance Fuel Max"

I guess what I am looking for is a balance of attributes for a tire but it leaves me only one choice for a` 155/80/13 but I will have to just roll with the KUMHO Solus KR21 in 155/80/13 for the smallest contact patch possible. I think the tires should have a pretty stiff/hard compound for the rubber judging on the miles people are getting out of them.(35,000-65,000 miles)
I do not want to go to much skinnier then that since I am used to the 175/70/13 tires with the extra 1" tread width. Tho the tires I have right now "Michelin Radial X" has been rated #1 by the Consumer Reports for rolling resistance, I don't believe everything I read and they may have not tested the sizes I have since they are pretty much not made anymore.

I am not a believer when it comes to tiny tires for MPG. I can not find any one that lost MPG by going with a slightly taller tire (less revs per mile).
Wider tires offer less rolling resistance with the same load.
At some point drag losses which increase by a factor or 4 every time your speed doubles will over come the lower rolling resistance which doubles with speed. I don't know where that point is, but I think it is roughly around highway speed for a car.
With a car you should be able to aeromod your way around the wider tire drag problem.
Also the idea of a small contact patch with a hard rubber compound does not inspire confidence with me.
I did the worst tire swap imaginable on my truck and I gained a barely detectable boost in MPG, that was going from a P235/75R15 that weighed about 26lb to a 2 inch taller 31x10.5R15 that weighed about 40lb. Both tires were made of hard compunds known for lasting over 60,000 miles.

When it comes to tires I have 2 rules.
#1, no tires made in china. Their quality control is garbage.
#2, no firestones, past performance is indicative of future results.

I like that imput :thumbup:
Well I want OEM size tires and guess I will try them out.!!! anyways! haha
I had to choose between the two and FIRESTONE is last on my list! lol

I will make a comparison against my used, old, Radial X and the new Kumho's.
I actually only need 2 tires but would like to get a good comparison and run a full set. I may try another brand in 175/70/13 if I am not happy with the only real 155/80/13 tire left on tirerack!

OK, let's start with the basics. Read this:

Barry's Tire Tech

and this:

Barry's Tire Tech

What you should get out is that there is a compromise involving Treadwear, Rolling Resistance, and Tracuion. You'll want to choose a tire that gives you the compromise you can be comfortable with.

Second is that larger tires give better RR - all other things being equal. That should open up a few more options for you - but sadly your speedo will be off.

Did you know the 155/80/13 tire is the OEM size for my corolla?
The 175/70/13 tire is smaller so going back to the 155/80/13 tire will be larger and match my spedo, this was just the comperable and closest replacement for the car at costco and they just put them on you know. It was when my exgf owned it. thanks for your idea but maybe you did not understand I am actually going back to stock size.

I currently have 175/70/13 size "Radial X" on it right now came with the car.
Section Width: 7" on 5" rim
Rim Diameter: 13 in 330.2 mm
Overall Diameter: 22.68
Sidewall Height: 4.82 in 122.42 mm
Radius: 11.32 in 287.52 mm
Circumference: 71.12 in 1806.4 mm
Revs per Mile: 917

I just found out 155/80/13 is the OEM size for my 90 Corolla Coupe.
Section Width: 6.10 in 155 mm
Rim Diameter: 13 in 330.2 mm
Overall Diameter: 22.76 in 578.10 mm
Sidewall Height: 4.88 in 123.95 mm
Radius: 11.38 in 289.05 mm
Circumference: 71.50 in 1816.1 mm
Revs per Mile: 913.8

Kumho - Solus KR21
Revs per Mile: 914
Weight: 14lbs

Maybe now you can see what I mean?

First - since you responded so quickly, I know you didn't read the links I posted. You need to do so, because they explain a lot.

Second, a 175/70R113 is LARGER in terms of load carrying capacity and that is the important issue - not diameter.