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I used cheap Chinese tires, new set every year, for eight years....40k mile warranty tires and drove them 55-60k at swap out. Set at factory tire pressure...60 psi is like playing Russian roulette, VERY dangerous. If not mistaken, I used the same for the Toyota Prius of the same gen...P185/65-15 @ $200 mounted & balanced (once) and were all-season tires....mpg loss was so negligible, it wasn't worth paying the if money for RE92 LRRT's. I have driven three Insights between two gen's....almost 1M miles between the three.
 

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Maxxis Mecotra ME3 165/65 R14 XL 83H is the tire I’d like to try. The chart shows it great for weather and MPG. Sadly I can’t find anyone to import a set.


 

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Just ordered set of Vredestein tires, based on comments on this forum. I have tread left on my Bridgestones, but the car has started to hydroplane at highway speeds and getting more use out of the present tires just ain’t worth the danger.

Since the Bridgestones were both howlers and skittish, I am hoping for a quieter ride and better handling. Either would be welcome, both would be stellar. I’m happy to trade a few miles per gallon for a more comfortable ride.
 

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Discussion Starter #24

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I like to drive in safety and comfort. I think with the excellent mileage these cars already get, it is time to think about safety first. Low Rolling Resistance Tires are fine as long as they do not compromise other factors, like Braking from Speed (see Tire Rack for specs). I think that there are a lot of factors that can influence gas mileage besides the actual tire. Has anyone ever compared 175 cm with 165 cm, we are talking about a very small difference! Perhaps less than 1/2", but here in Oregon where it rains a lot (just like Pennsylvania) we need a tire that is safe enough to stop in time. High pressure for the sake of a few miles per gallon is saying that you're life is not worth a million dollars!
(...or more). Stoppiong in time is critical to safe driving. That's my two cents worth in this conversation.
 

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So like, weight is low and maximum pressure is higher, but do we know anything about MPG? I thought the LRR tires are harder so they have a smaller contact patch with the ground, but this tire is boasting about its handling characteristics in the description.
The government paper which Minor listed in the other thread has some good information on how the trade-offs are made. There is no free lunch.

I guess the question really is, which better handling/riding tire gives up the least mpg, but it is going to be tricky because of the LB issue. LB is still a marginal issue at American cruising speeds, so increased rolling resistance probably has an outsize impact because it lowers the amount of LB time.

Because of the LB issue, Insighters have a rather special problem and I doubt anyone is going to study it adequately:(
 

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See my signature for my tires. I've driven on them in temps from 0*f to 98*f at times and for 250 mile commutes to 4" of snow. Drove to Chicago from my home near Cincy, 84mpg on that commute. Averages mid 60's with a decent variation in elevation change on my daily highway commute. Unfortunately you'll have to custom order them from Europe. I was lucky enough to get them second hand from a local guy that only had them on his insight for a month before selling the car. Once the tread has been exhausted I'm not sure if I'll replace with the same or not due to the high cost.
 

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I got sticker shock when I saw the price too! $154 :oops: They are some of the quietest and smoothest tires I've driven on tho.
 

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So like, weight is low and maximum pressure is higher, but do we know anything about MPG? I thought the LRR tires are harder so they have a smaller contact patch with the ground, but this tire is boasting about its handling characteristics in the description.
I was just going by my suggestion that lighter weight tires have less material to flex, and higher pressure reduces flexing. That's the strategy used on road bicycles, for example. Here's some info on Bridgestone specialty LRR tires. Comparison of LRR 155/70R19 tire at inflation pressure of 320kPa to a conventional tire with an equivalent load capacity, 175/65R15, inflation pressure: 210kPa.

 

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Could we try a rolling resistance comparison by parking identical cars with different tires, inflated to same pressure, on level, on same pavement, and hand towing them with a spring scale in the tow line? Compare tension to keep cars rolling at a persons walking pace.
 

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Could we try a rolling resistance comparison by parking identical cars with different tires, inflated to same pressure, on level, on same pavement, and hand towing them with a spring scale in the tow line? Compare tension to keep cars rolling at a persons walking pace.
Yes, but it is very difficult to get repeatable numbers. I tried to do some coast-down testing when I first got my car, and it is tough.
 

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I actually do it going up hill.in neutral with dead motor. different speed by the same landmark .at Different tire pressures.that's how I know 100 psi is better than 90 psi.
 

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The folks over on ecomorder have tried to test air pressure effects. They use roll down distances to approximate the effect. There are still a lot of variables to control like transmission temperature, tire temperature, etc.

I've tried measuring tire pressure effects using start from a downhill to gain speed and then measure the coast down distances from a fixed point. By tinkering with the starting point on the hill, you can set your test speed. The speed has to be well controlled, because the rolling resistance also changes with speed. BTW, improvements in rolling resistance for the RE92 taper off rapidly after about 60 psi.

When trying to develop/train my hypermiling skills(see signature), I had pretty good results just resetting the FCD and driving the same 2 way course several times. It would help to have a clutch switch so that the highly variable lean burn could be disabled since the average amount of LB while on the course has a profound effect on the results.

There are many practical problems with using a weight scale particularly if the data is to be read manually. Another problem, if the drag is to be measured at reasonable road speed, is finding a long course which is reasonably flat. Then, the whole experiment is probably illegal on public roads :(

I suppose that a digital scale might be found which would have a data readout. That could be plugged into a data logging program and the data could be integrated over a two way course for a reasonably accurate. If one reads the study posted by minor4326 in the other thread, one realizes just how difficult a measurement of rolling resistance would be without specialized test equipment.
 

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I'm my opinion the only way to determine the LRR of tires is to have a systematic approach to collect data such as what Peter mentioned, measure using a Dyno.
 

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I'm my opinion the only way to determine the LRR of tires is to have a systematic approach to collect data such as what Peter mentioned, measure using a Dyno.
Yeah, the rolling resistance is such a small quantity and the required resolution so fine that only special machinery is going to slice and dice the data properly. The NHTA study you cited in the other thread, and here:


shows the standard machinery on p10 of the study.

Though the machine has a load cell like a dyno, it is quite different from the standard dyno. The standard dyno measures either engine or wheel power with a variable load and a load cell. The tire machine has an electric motor and load cell to measure tire drag.
 
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