Honda Insight Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
43 Posts
Discussion Starter #1
Ok Folks;

I do a 160 mile round-trip daily commute, on mostly flat terrain, on a wide-open 4-lane highway with very little traffic (relatively speaking). I bought my used 2000-model insight with high hopes for high mpg. My daily commute was perfect for coaxing high MPG out of an Insight.

However, I was having a great deal of trouble getting the car to achieve a reasonable mpg number. I couldn't get anywhere near 65mph and 70mpg. In fact, I usually had to slow down to 55-59mph to get above 62mpg. I found insightcentral and only got depressed at seeing the mpg numbers others were achieving. My manual transmission car's lifetime mpg rating is only 55.7mpg: I worried that somehow I had bought a lemon. This went on for a few weeks and I was very disappointed. :cry:

I had some things done to the car that helped quite a bit. About a month ago, I had a brake problem fixed and that bought me about 8 mpg. But that's when I was getting way down into the 50mpg range, and that boosted me to about 56-58mpg at 60-65mph. Better, but still not what I had hoped for. "65 at 65" was my goal.

When I saw the discussion about tire pressures here on insightcentral, I thought you guys were loony tunes. :wink: 50psi in a 42-psi rated tire? I expected to hear tales of tire explosion, but after watching and reading for a few weeks, all I heard was good stuff back from the "50psi crowd".

What the discussion about tire pressure DID do was make me focus on the tires, and what I found was sobering: every one of my tires had no more than 32psi in it: they had been set at the last service to that by someone who didn't know these were higher pressure tires. I grabbed one of those little "stick pressure meters" and decided to inflate the tires on up to nameplate rating, 42psi or so.

The difference in the mpg and speed I could achieve was clear: I picked up another 5-6mpg, but more importantly, I picked that improvement up UNIFORMLY: I could ease on up to 60mph, and still get 60mpg: My goal of "65 at 65" was within shooting distance! :D

This was a revelation: the overinflation of the tire made a tremendous difference in mpg, and allowed me to keep that mpg up at a higher speed. I enjoyed the increase for a tankful (about a week) but by the end of the second tankful, (into the second week) my mpg achievements were gone. In fact, I had another problem: I couldn't seem to keep my battery charged up: I was now depleting it during small amounts of stop-and-go city driving, and it was NOT getting charged up on the long highway drive home. More importantly, my mpg was dropping way BELOW 50mpg at 60-65mph. It's a scary thing to see 48mpg, a depleted battery AND bad performance... :shock:

My first thought was that my battery pack was dying or something. But then it occurred to me that it had been two weeks since I had checked the tires: my experience from cycling tought me that high pressure tires do lose air faster, and I hadn't checked. Worse yet, when I did check the tires last, I used one of the cheap, inaccurate "stick" gauges. I knew better than this and got my nice dial pressure gauge that would hold the pressure reading after you took it so you could bring the gauge face up into the light and see it clearer.

So: I had to get gas yesterday, and I'd just found a gas station with reasonable prices ($1.53/gal here in central NC) and free air (an extreme rarity these days). I filled up and moved over to the air hose, and this time I had my accurate dial pressure gauge with me. What I found stunned me: three of the tires had only dropped down to about 38psi (warm) from the 44 (cold) I had set them to. A fourth tire had dropped down to 23psi warm! What worried me most is that it was possible the tire had never reached the 44psi I tried for, because of the inaccuracy of the "stick" gauge.

So, anyway, I topped off all the tires, and this time I "went for broke": put them all at a solid 50psi, as read by the accurate gauge.

I expected the ride to get very noisy and uncomfortable: it was no worse than 40-44psi. I did find myself having to be more careful going over railroad tracks or with unavoidable bumps and potholes. A tad bit of an increase in road noise, but nothing significant. I was cautiously pleased.

Then I got out on the highway for the drive home, and the ride of the car was completely different! At 50psi (as measured by the accurate gauge) the car would kind-of "glide" along on the highway. Effects from drafting or "surfing" were much more noticeable on the instantaneous mpg bargraph. I had set one of my tripmeters to record only the highway mileage: this was to be the litmus test: what would happen on the 73miles of highway between me and home?

Arriving home that night, I saw what I didn't think possible: I averaged 65mph and managed 70.1mpg. I did a "little" bit of drafting and surfing, but not a huge amount. I had a tailwind part of the way, but not very much. So the results seemed good and not a fluke of wind or traffic. More importantly, my battery charged up nicely, even though I required some assists on some of the hills going home. I was amazed at the difference.
So, here are my preliminary conclusions:

1. 44psi is a good place to put your tires, but 50psi is even better. I've had no trouble with that in the tires, save for a harder ride over railroad tracks and potholes. I just slow down for those objects and it helps.
2. Check your air pressure frequently, at least once a week.
3. You can have only one tire lose it's pressure and it'll make all the difference. I had only 1 tire go down and I thought my battery pack had failed! :)
4. An important trick to getting high mileage in the Insight is "proper tire air pressure management".
5. Finding a gas station with free air is worth paying a few extra cents per gallon because it costs 50cents most places and the air compressor there won't run long enough to get to all four tires.
6. Buy a nice dial reading air pressure gauge, one with a pressure release button that lets the meter "hold" the pressure reading after you take it off the tire.
7. Check that the tire valves are tightly screwed down in the valve stems. There's a tool you can get at bike shops to do this with, just ask for something you can use to tighten "schrader-styler tube valves".
8. I wasn't actually sure I believed in this talk about "lean burn mode", but getting the tires up to 44psi, and then on to 50psi, helped me see this on the mpg bargraph. I don't know if the Honda engineers are laughing at us or not, ;-) but I can definitely tell when the car goes into NOX purge mode, and I can see a difference in how the car behaves when I let off on the gas and "feather" the pedal into the higher mpg range.
9. I'll wrap up my accolades with a WARNING: at the much higher tire pressures, the car does not handle well on road seams. And I mean ANY road seam or imperfection. In fact, it wants to "jump off" the road if you hit a seam at the outside white line. So my only warning from "50psi land" is to always "drive the car": don't tool along using only one wheel, don't talk on the cellphone, and pay attention to the road. But then, all Insight drivers know they have to drive this way anyway, right? :)


Well, I apologize for my verbose message, but I'm just putting out information with more detail, something I hope is of help to those of you out there who, like me, agonize about pushing the tires beyond "nameplate pressure" and who also know that when the tires heat up, you get another 2-4psi, added reason for concern. I went on up to 50psi and it really helped on the highway to reach the mileage numbers I needed. More importantly, I found that when one or more tires drops a lot of pressure, that can look like a malfunction elsewhere in the car. So get a good tire gauge and watch that pressure, at least once a week.

JKB
 

·
Premium Member
Joined
·
4,942 Posts
Hi JamesKB,

A good complete first hand account of tire pressure.

As far as the over-inflation concerns go:

I have personally seen 32psi rated tires go for many hundred miles at 80!!!psi without failure. Although overinflation wear would have severely shortened this tires life had it continued long enough.

From my reading on the topic there is a large percentage margin of safety built in to most tires in relation to inflation pressure (100+%). As you have noted just be aware you are using some of this margin and if you happen to be in the wrong place at the wrong time...


John K. Bullock
Knoxville, TN

aka. Insightful Trekker
 

·
Registered
Joined
·
211 Posts
commute...

That is a LONG commute. How did you end up working so far away from home?
 

·
Registered
Joined
·
43 Posts
Discussion Starter #5
Re: commute...

Insighter said:
That is a LONG commute. How did you end up working so far away from home?
I live in central NC, in what is known as the "Research Triangle", which has been home to business units of several large telecommunications corporations. We have an unemployment rate here of "only" 4.8%, which works out to just shy of 30,000 people unemployed here.

Last July, I became one of those unemployed, and hit the bricks hard. Despite having good credentials and employment history as a UNIX system admin there just weren't any jobs. I began to look outside the immediate area and found much more opportunity. I planned to have to leave the state when I realized how much worse it is here than other places.

Then I found a job in NC, but 80 miles to the east. The time of the commute (about 1.5hrs) is a burden, but not incredibly so. The mileage, however, was killing me: I was tanking-up a full size GMC pickup three times a week at $40/fillup. $120/week for gas and about 1.2hrs/week spent just pumping fuel were killing me.

I'm not yet in the financial position to be able to move. Stuck with the commute for the forseeable future, I started working on a spreadsheet of small cars to see if it made economic sense to buy something else to make the commute, to see if it was cheaper to get a small car and put those $$ toward the new metal instead of more fuel.

I was skeptical, and my skepticisim was borne out by the spreadsheet. "Standard size" cars fell by the way, as 28-32mpg wasn't good enough to swing the cash in favor of the car. Smaller 4-door cars still weren't good enough, since 38mpg didn't yet achieve breakeven for anything less than $10k. The Ford Escort/Focus came close, and the Geo Metro closer yet, but I didn't want to spend any money on an American designed car and I've had a Metro before-a distinctly unpleasant experience.

The Prius and the Insight had gotten a lot of press around this area, being a concentration of technology companies, you find a lot of people around here interested in that type of thing. But I didn't think I could get either car used: who in their right mind would want to get rid of one with gas prices heading toward $2 in this area?

Much to my surprise, I found more than a half-dozen Insights listed on Ebay. Buy a car on Ebay? You gotta be crazy. But the prices were in my range, just a shade over $10k. I found one with awesomely low miles for under $11k. Poked the numbers into my spreadsheet, and my eyes popped out: for the $420-$$460 I was spending on fuel would make the Insight car payment, insurance, and buy all the gas...as long as the car got over 54mpg. So I went for it and after some misc. gyrations and minor problems, I've been using it to make a 160mi round trip commute every day.

I've finally gotten to the point where I can reach 68-70mpg if I work at it. That lengthens the commute by about 15-20 minutes, depending on traffic at the endpoints. If I go a little faster, I get around 63mpg. If I "romp it" (70-75mph) I'll drop to right around 60mpg. In all these conditions, I still make the fuel mileage goals and still can pay for the car.

The insight has been a real lifesaver for us. I wouldn't have been able to take this job if I hadn't found one: it was just costing too much money to commute. I could've taken a cheap apartment locally and just commuted on the weekends, but my boys are at a stage in their lives (two teenagers) where that would be asking for trouble, and we're not going to give up on them now when they've all done so well this far. :)

Anyway....that's the long story. We all love our insight. I'd buy another one if I had the money, and I hope one day we do. And finding this website has been awesome: everyone on it loves their car and seems to be willing to work to get their cars to perform better, AND share their successes and failures (just as important!).

JKB
 

·
Premium Member
2001 5S "Turbo"
Joined
·
11,113 Posts
Tire pressure

If you want to see a real shocker.......Look at the specification sticker on the drivers door jamb. (TIRE SPECIFICATIONS)See the max psi at max vehicle weight. ?????????? .......Snaking is no problem, "KEEP THE FRONT END POINTED STRAIGHT AND THE REAR WILL FOLLOW"... DON'T OVERCORRECT your steering........
 

·
Registered
Joined
·
211 Posts
I see...

Wow, I don't envy you the commute, but it sounds like you are making the best of it. Now all you need is XM radio (my next modification).

Move to San Diego and enjoy the year-round perfect weather (if the boys are reluctant, remind them we have beaches and with beaches, girls).
 

·
Registered
Joined
·
1,240 Posts
I took a 3000 mile vacation with my tires at 50psi and not one problem! The tires are actually safety rated for more. They will also wear much more evenly at 50psi.
 

·
Registered
Joined
·
211 Posts
50 psi

You are the first person to say that 50 PSI will make the tires wear more evenly. Everyone else I've read and heard says the opposite. Which is true?
 

·
Registered
Joined
·
2,448 Posts
I have a theory that the center belt on the tire is so stiff on these low rolling resistence tires that higher pressures tend to push out the outer portion of the treads out more than the center like conventional wisdom tells us. I'd be curious to see what the results are like after say 20,000 miles with the tires inflated to factory specs or even lower vs 45 50ish. Otherwise there would have to be some pressure that could get these tires to actually have some wear in the center of the tire rather than at the edges. I've got 14,000 on mine and I've kept the tires at 45 psi and I can already see the wear patterns at the edges of the tires starting. All well, I guess I'm sort of already planning on replacing them at around 30,000 anyways, I coudln't complain if I got that much life out of them with the way I drive.
 

·
Premium Member
2001 5S "Turbo"
Joined
·
11,113 Posts
Tire wear

The std. Insight tire is rated at a "260" wear factor. With proper inflation they will be good for at least 40,000 miles. I run my tires with 48-50 psi at all times. The sides show a lot more wear than the middle. Replaced mine at 40,000 and now have 26,000 on the replacements. In the area I drive there are a lot of curvy roads, hence the wear on the sides.
 

·
Registered
Joined
·
32 Posts
at high pressure the tires lose air

i see the same thing, 3 of my tires lose 3-5# a week and another one (right front) loses more, maybe 7# a week. good idea to tighten the valve, i'll go do that now. anyone have opinions as to what rate of loss would cause the dealer to look at and fix the problem?
 

·
Premium Member
Joined
·
4,942 Posts
Re: at high pressure the tires lose air

rone said:
i see the same thing, 3 of my tires lose 3-5# a week and another one (right front) loses more, maybe 7# a week. good idea to tighten the valve, i'll go do that now. anyone have opinions as to what rate of loss would cause the dealer to look at and fix the problem?
If the tire valve cores are loose that will be your leak. The cap is simply designed to keep dirt out.

_After_ you have the tires(s) in question checked for punctures, which for some types of damage requires dismounting the tire. Then you have a case for warranty consideration of a leaking rim (extremely rare in my not too small experience).

First have the tire soap bubble checked. Its a bit tricky discerning some small leaks from the soapy water foam that will be coating the tire. Second have it bubble checked in a tank of water (after completely rinsing the soapy water off the tire). Finally I have experienced various types of fine wire penetrate the tread that are only clearly seen from the smooth inside of the tire.

Unless you purchased some type of extended warranty that additionally covers tire punctures (and that is by far the most likely scenario) its your nickle.

John K. Bullock
aka Insightful Trekker
 

·
Registered
Joined
·
16 Posts
???

You all say it wears more on the outside of the tires when over-inflated. I'm almost positive that this is uncharactoristic of most tires. I've seen and heard of under-inflated tires wearing on the outsides. So it seams to me that it would make sense for an over-inflated tire to wear in the middle first. ---Tell me if i'm just being insanely ignorant---
 

·
Registered
Joined
·
242 Posts
Apparently, from what's been posted here at IC, these tires have stiff sidewalls - if this is the case, that would account for wear on the outer edges of the tire.
 

·
Registered
Joined
·
51 Posts
For the majority of my tires 58,000 mile history they have been inflated to mid thirties psi and they have worn more heavily on the edges (recently upped to mid forties after reading IC) . 95% of my driving is done in a 700 mile weekly weekend roundtrip home on fairly straight highways. They have been rotated 3 times and still have a fair amount of tread. I'm hoping to have them last the summer and replace them just before my next inspection in Sept. This will give me nice new thick tread for the winter. How do you guys decide when the tires need to be replaced?
 

·
Registered
Joined
·
320 Posts
I've heard testimony now of people with both overinflated and underinflated tires say there's wear along the outside. I haven't heard ANYBODY say they had tire wear in the center. I've heard people say that they EXPECTED center wear because of overinflation, but I haven't heard anyone confess to actually seeing center wear.

Has anybody seen center wear on their tires?

I suspect that the steel bands in the tires are so stiff that they minimize the shape distortion of the tread regardless of inflation, and the outside wear people are seeing is almost completely from turns. We wear the front tires from turns, then we rotate the tires. The rear tires basically get no wear at all while on the rear.
 

·
Registered
Joined
·
30 Posts
when to replace tires

one way you can judge if the tires need to be replaced is to take a penny and put it into the tread with the top of the penny touching the tire. if you can look at your tires at tread level and see the top of abe's head, your tires probably need to be replaced. if you cannot see the top of abe's head, your tires are probably still good to go.
 

·
Registered
Joined
·
16 Posts
---You could also just look at the low tread indicators.

---If nobody has had tread wear in the center, then can't they be inflated much furthur withour having any affect on the life of the tire. It also seams to me that the lowest rolling resistance would occur when most of the wieght is distributed on the center tread, like on a road bikes tires.
 

·
Premium Member
Joined
·
4,942 Posts
lethostigma said:
<huge snippage>

How do you guys decide when the tires need to be replaced?
The offical rule of thumb is whenever the depth of the grooves in the tread is less than or equal to 2/32" _anywhere_ on the tire. Abe Lincon's head on a US penny is about this distance from the edge. Hence the common use of a penny as a tread depth gage.

As you might imagine there are many tires out there on the road right now wih less that this spec. One of the very best "tread" design for _DRY_ pavement is no tread... BALD! However, use a garden hose to wet the road and it will almost "feel" like driving on ice.

It is appears common for the OEM Insight tires to wear on both the _outside_ edges reguardless of inflation or driving style. As mentioned in these threads probably something related to the low rolling friction design.

The lack of grooves on the edges will limit the tires ability to squeeze water out from under the tire, although the inner grooves will still be able to squeeze it out the back. This will limit the tires wet weather handling. Use caution.

Depending on your speed and the amount of water your trying to plow the tires may still be useable until the center grooves approach the 2/32" limit. But watch the edges for _any_ signs of the cord/belt showing. If so replace the tire(s) immediately.

If you forget this fact or traffic is pushing you then the money your trying to save in rubber will be spent on bumpers, fenders or worse!

John K. Bullock
aka. Insightful Trekker
 
1 - 20 of 24 Posts
Top