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Discussion Starter · #1 ·
The next paragraph is background information of why I wanted to compare tires. If you just want to see the test and results, go to the next one.

Concerned that I wasn’t doing something right, or that the terrain in my commute was unusually rough on mileage, I wanted to explore the possibilities that might increase my mileage. My car, a 2000 (#2757) had 32000 miles on it when I bought it. I had posted several times about my mileage or how the rain affects it etc. but now that the weather was warmer I thought I should be getting better mileage. My best tank to date has been 67.9 which I had achieved 3 times. My average consists of mostly interstate driving, but I do a fair bit of around town on the weekends 66mpg for 4,000 miles. Since I was seeing posts of people getting 80s-90s or more, I wanted to increase mine so I could run the A/C this summer and still better my old mileage by at least 3 times. I installed the simplest warm air intake, and use the radiator block when it is cold. Rick Reece lives in Greenville about 30-35 miles away from me and he has been very cooperative in offering advice and stopped by on his commute to show me his car since I had never seen an Insight up close at that time. After talking with him I decided I would get a used one since that was all I could afford. For the most part is has been a great experience for me and I really like the car. Rick has a lot of stuff on his car, and it should be heavier than mine, but gets 20mpg better than I do on the highway. There are other factors like distance of commute, in town driving etc, but I thought I should be able to get better mileage. My car came with an Alpine Stereo, MBQuartz speakers, Sumitomo HTR200 175/65 14 tires and my newest discovery a K&N air filter. It is in perfect condition and it seems to me the person who had it before me had done his homework on the Insight.

I needed to know if I could attain significantly better mileage by going to the OEM tires, or at least enough to recoup my investment in a reasonable time. Rick had graciously accepted my offer of making a controlled (sort of) run and then switching tires to see if there was a significant difference. Our test is far from scientific, but it gave us an idea of the difference between the two (your mileage may vary :D ). The Sumitomo tires are considered to be low rolling resistance (3rd on the list from greenseal.org).

Rick came over to Spartanburg yesterday and we decided on at least a 20 mile run and I had just received my OBD-2 scanner system, so I could at least verify some information. We did one run and then did a repeat after switching wheels and tires on the cars. I followed him both times, but not very closely as I would fixate on the FCD sometimes, which would probably introduce a fair bit of error. Fortunately he used his cruise and throttle controls.

Track info (from Rick’s gps): 25.7 miles by GPS over rolling hills, Avg. speed by GPS was roughly 55 mph, Min/Max elevation 753/940 ft MSL. Track included 2 stop lights at the turnaround point. Temp 72F first run 76F second run. (“I think the indicated temperatures were a few degrees higher than the real temp as I had the radiator block in thus it probably made the temp warmer than it really was”. (Rick))

My intake air temperature ranged from 109degrees to 113 degrees depending on the engine load. Rick’s was around 146 degrees if I remember correctly. According to the advertised weights for the tires, the Sumitomo’s are only 2 lbs heavier. I didn’t have any scales, so we just compared the two by lifting. The Sumitomo tires felt more than 2 lbs.


Insight #4738 [moderator insert, Rick Reece's](Approximately 150-200 lbs heavier due to full fuel tank, insulation, stereo equipment and heavier driver and floor jack).


Bridgestone tires RE-92 165/65 R-14
Odometer distance 25.9 miles
MPG: 91.6
Max engine load: 94.1% OBDII reading
Max speed: 66.7 mph (GPS)
Avg. Speed 54.7 (GPS and includes turnaround point)

Sumitomo HTR 200 175/65 R14
Odometer distance 25.2 miles
MPG: 78.2
Max engine load: 96.8% OBDII reading
Max speed: 64.3 mph (GPS)
Avg. Speed 53.9 (GPS and includes turnaround point)


Insight #2757 [moderator insert, originalbadbob's](approx ½ tank fuel)


Bridgestone tires RE-92 165/65 R-14
Odometer distance 25.9 miles
MPG: 94.9
Max engine load: 94.7% OBDII reading
Max speed: Approximately the same
Avg. Speed: Approximately the same

Sumitomo HTR 200 175/65 R14
Odometer distance 25.2 miles
MPG: 80.3
Max engine load: 96.9% OBDII reading
Max speed: Approximately the same
Avg. Speed: Approximately the same

My driving impression is that the Sumitomo’s track quite a bit better than the Bridgestone’s, ride better, are quieter and corner significantly better. The IMA was significantly higher with the Sumitomo’s when climbing hills without downshifting, which might make it easier on the batteries in the long run (although I usually downshift on my normal commute). The difference in mileage for our simple test was approximately 15% for both cars. If I was 25 years younger and still sliding around corners, I’d definitely opt for the Sumitomo over the Bridgestone.

For the type of driving I do, I’m going to switch over to the RE92’s as soon as they get here. I ordered a set when I got home. It looks like Roadway Tire in Pompano Beach, FL has the best prices at $47.24 each. Shipping might be more than some other places, but the bottom line is probably better. $223.81 to my door seems pretty good. roadwaywholesaletire.com
 

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THANKS :!: Bob & Rick Reece for your enlightening work.

Bob, I hope you don't mind my [moderator inserts] in your post above. It's just that I had to read it 3 times to tell which car was which and what really happened.

EDIT: Feel free to remove my edits and or change your post as you see fit.

GREAT post! :D
 

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Discussion Starter · #3 ·
Thanks John,
I only read it a couple of times, but didn't catch that. Don't mind a bit about the additions, and I'm always open to suggestions.
It was a fun afternoon, and I know Rick's time is always at a premium so I really appreciate him spending an afternoon collecting data and getting our hands dirty.
The first thing he said after the second run was "I want my tires back". I guess I'll have to turn up my stereo a little when I get the RE92's, but it's still quieter than my old car.
 
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Hi Originalbadbob:

___Great post! Thanks to both you and Rick Reese for doing the analysis for current and future Insight owners around the country and the globe.

___And with that, I am glad to see your little beauty is back on its LRR OEM rubber as she was truly designed for them. The longevity of your pack will be much increased, the longevity of your brand new RE92’s at 50 + #’s will be a vast improvement over what you would have received from the Sumitomo’s, and the FE you will now achieve will make the whole ordeal worthwhile to say the least.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1wvzxyeo][email protected][/email:1wvzxyeo]
 

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Re: tire pressures?

Dougie said:
Were the tire pressures the same?
Good question. Guess we'll have to wait for Rick or Bob.

The Sumitomo's are rated for 51 psi according to TireRack and AFAI remember Rick Reece "over inflates" his Bridgestone's to around 50 psi.

If so then the difference is nil given the other possible variables in this type of test. And about 3% reduction of the Sumitomos is apparently due to differences in circumference as shown by the differences in the odometer readings between the two cars when the tires were swapped.

So "true" differences in rolling resistance and the resulting reduction of MPG in the hyper mileage range is closer to 12%. The MPG difference will be less the more aggressively the car is driven.

HTH! :)
 

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The 2 results are very consistent for a "real world" test.
Another factor that should be considered is tire diameter.
The 175/65R14 tires have a larger diameter so the vehicle will travel a further distance then the computer calculated. So the actual fuel consumption is slighter better then the FCD states.
But the "tire calculator" reveals that the difference in odometer reading (circumference) between the 2 tires is only 2.3%
http://www.miata.net/garage/tirecalc.html

originalbadbob wrote:
"The difference in mileage for our simple test was approximately 15% for both cars."

I suggest the difference between the tires is (15% - 2.3 % =) about 13%.

Good job!
 

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Insightful Trekker,
You replied with the same thoughts about tire diameters at the same time but you beat me to it by seconds!
 

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Discussion Starter · #10 ·
Hi guys,
We were both running 50 psi. Like I said, it wasn't a very scientific test, and to attain more accuracy, we would need to run them over a longer period. It did, however, give me some numbers to compare, and 13% difference is close enough for me. What we did see, is that the change was about the same for both cars, which we were hoping for. I would lose some ground on Rick, because he was in his automatic commute mode, and I was trying to do the best mileage I could.
I'm confident that I will increase my mileage with the RE92s, and that was the whole purpose of the test. I'm sure we could improve the testing, but it was fun, and if anyone is coming through Spartanburg,SC sometime, we can try it again.
Thanks again Rick for your help.
Robert
 

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Nice comparison guys. The Sumitomo's are supposed to be LRR too right? Just goes to show just how good our Potenza's are when it comes to energy conservation.
 

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originalbadbob said:
The Sumitomo tires are considered to be low rolling resistance (3rd on the list from greenseal.org).
Bob,

I went to the website but couldn't find anything on tires. Could you post a specific link?

Thanks!
 

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Thanks for the link!

But I don't get it! First I thought, great! They actually measure rolling resistance as a number. All I need to do is buy the tire where the number is the lowest! - WRONG!

Apparently, the "rolling resistance coefficient" is not an absolute measure of resistance, but some sort of relative factor that is pretty meaningless by itself (at least to stupid me).

How could a 235 wide winter tire (Michelin Arctic Alpin) get a better score than a 185 LRR summer tire like the Nokian NRT2? This makes no sense at all! Even if Michelin was a lot smarter than Nokian, there is no way a tire with almost 50% extra tread could be better than the narrower one. And any decent winter tire has much higher resistance than even an average summer one.

I can't help the feeling that they are not comparing apples to oranges, but maybe to watermelons...
 

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Discussion Starter · #15 ·
Hi Armin,
Like you, I'll bet the rolling resistance is some kind of ratio that is similar to the coefficient of drag as compared to a semi truck. They are low by definition, but still have a lot of drag, so maybe it is some kind of ratio that has the size in it which makes the coefficient low, but still are quite draggy :?: . They might get the rolling resistance figures from the kind of rubber, tread design etc, and compare the same size tire to the same size tire since not all tires are made in all sizes.
I'll bet the weight of the tires makes more difference than anything unless you only accelerate once per trip and the road is perfectly flat.
Tire design is not an exact science. When I was on an IMSA team 20+ years ago we were helping Goodrich develop the Comp T/A tires by running them on a factory backed Mazda RX-7. When we did the PR thing at the factory, they gave us a very extensive tour. The artists (yes that's right, artists) come up with the 'look' of the tread and tire. They give the engineers several designs to compare and they check all kinds of parameters on some hand made test pieces. From there they go back and forth until they get to the point where the engineers and marketing people agree that this is the one we can work with. Then it is mostly the engineers that modify different construction types to make it handle as good as they can with different compounds, side wall flex etc.
It was weird to think that the artists come up with what they think will sell and then design around that. I guess you gotta start somewhere.
robert
 

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Anyone ever heard of or seen:

Sonar S-665 tires?

The new GF's CVT (2002 CVT) has a set on it, and it seemed to get pretty good mpg. We were using the AC and going pretty fast and still getting tanks around 50 mpg or just shy of 50 over several tanks in hot weather from GA to MA to WY to CO to CA.

I never heard of them. I can't find any information about them. They have pretty squishy sidewalls, but the mpg seemed to me decent for a CVT with it fully loaded with gear and two people and AC etc. etc.

Anyone know anything about these guys?
 
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