Lower gas mileage with larger tires

[Willie Williford]

It's one gauge. You can get a boost gauge or a vacuum gauge individually.
HTH
Willie

[wtoguru]

Use the actual fill up numbers in this case. Typically, larger tires will lower the gas mileage, this is normal.

[OttawaGeorge]

I don’t have near as much experience with the car as most on here and a newbie can’t absorb 10 years of posts in a month but I can chime in what I know from being a car nut for a long time.

The Insight is already geared taller than anything I’ve ever driven. Taller tires make it harder time getting into 5th gear and will have to downshift sooner on hills etc. Compounding that is the drag from a wider, non Insight optimized, less LRR tire. The taller car will raise the car and open the gap underneath the car increasing the drag coefficient because you’re opening up the gap underneath the car. The spats that are designed to direct air around the 165 tire will now put that fast moving air directly onto the tire surface and bugger up the flow. As I learned from a post just above anything that makes it hard to get into lean burn kills FE.

Skimmed through the Insight resource manual for the first time yesterday and it really drove home how everything on this car is designed for one purpose...seems wrong somehow to bugger it up. The mods that work to improve FE seem to be the ones that allow you to feed your anticipation of what traffic is doing into battery and regen management and to bring power into the car from an outside source. I'm sure I've read a thousand posts and I've found very little that deals with improving the car itself.

[Printermobile]

So I am pretty new here, but it seems that a lot of these answers are going to be useless. I've been trying for months to get some original Bridgestones. No luck.

I was looking at the forum to see if anyone knows how to hack the computer to adjust the speedometer for 185/60R14 tires. It can't be that difficult, is it? Turns out I am not alone.

Regardless, since these magical RE92 tires in our size are gone we may need to resort to offering more updated advice.

Any recent advice to help with the tires and sizes that are currently available in regards to speedometer adjustment and fitment issues?

[aisbell]

Originally Posted by Printermobile

I've been trying for months to get some original Bridgestones.

Several people have reported recent success ordering RE92's from TireBuyer.

[Jivko57]

Good evening ,
I just ordered 4 RE92 165/65/14 from tire buyer yesterday. price with tax came to 392, and free shipping. some places offered lower price but shipping was extra.
in 2009 I bought from tire rack but they were on back order this time.

I will get the tires hopefully next week and will ran to walmart to have them installed.

that will probably be another 40-60 dollars .

I was not planning to change tires soon the rears had good thread and the front were getting close to bold but still legal....

I think i had ~50k on the rear ones and some more on the front ones, or vice-verse.

Unfortunately yesterday morning i got a flat and drove around for a while without noticing,
finally i got on the highway and the noise became too loud, also the mpg was terrible. It was a rear tire , I put some air in and drove 1 more mile to the closest tire center(walmart) by the time I got there it was completely flat again . They fixed it but warned me that it may fail soon , the sidewalls are seriously impaired on that tire...

so I went online and after some search bought the set from tirebuyer . So far it looks like a great deal but I will wait to get the tires and put them on the car before making any recommendations.

[Eli]

Tire rack has them in stock now.

[Jivko57]

Originally Posted by OttawaGeorge

I don’t have near as much experience with the car as most on here and a newbie can’t absorb 10 years of posts in a month but I can chime in what I know from being a car nut for a long time.

The Insight is already geared taller than anything I’ve ever driven. Taller tires make it harder time getting into 5th gear and will have to downshift sooner on hills etc. Compounding that is the drag from a wider, non Insight optimized, less LRR tire. The taller car will raise the car and open the gap underneath the car increasing the drag coefficient because you’re opening up the gap underneath the car. The spats that are designed to direct air around the 165 tire will now put that fast moving air directly onto the tire surface and bugger up the flow. As I learned from a post just above anything that makes it hard to get into lean burn kills FE.

Skimmed through the Insight resource manual for the first time yesterday and it really drove home how everything on this car is designed for one purpose...seems wrong somehow to bugger it up. The mods that work to improve FE seem to be the ones that allow you to feed your anticipation of what traffic is doing into battery and regen management and to bring power into the car from an outside source. I'm sure I've read a thousand posts and I've found very little that deals with improving the car itself.

George you got it in a nutshell, the car is perfect for fuel savings, and is quite well designed, the issues more often are coming from deterioration and age. once one component is under performing, then the lean burn use is decreased and mpg goes south.


to be able to get to 80 mpg usually it is not necessary to try to modify the car, but rather to keep it closer to the factory condition. and to slow down.

regarding the outside source, the lack of a grid charger is a design flow, the car is depending on the IMA system to supplement an engine that is to anemic by itself. The IMa system uses electricity and then puts more pressure on the same weak engine to replenish what has been used. wasting more fuel than it saves, as the conversions to and from electric power take their tall. Not to mention that the ima battery gets easily out of balance...

[aisbell]

Originally Posted by Jivko57

the car is depending on the IMA system to supplement an engine that is to anemic by itself. The IMa system uses electricity and then puts more pressure on the same weak engine to replenish what has been used. wasting more fuel than it saves, as the conversions to and from electric power take their tall.

The IMA system is vital to make the whole package efficient and drivable under most conditions. An ICE is most efficient at low engine speeds (less frictional losses) and high throttle openings (less pumping losses), but such an engine is gutless pulling away from a stop up a slight incline with the A/C on. The IMA motor makes such situations tolerable.

I disagree with your assertion that the IMA system wastes more fuel than it saves. Without the IMA system, autostop, with its ~15% fuel savings in urban driving, would not be possible. Without the IMA system, energy could not be recaptured from braking. These fuel savings more than offset the addition fuel burned during regen if the IMA system is working well. We know that driving style greatly affects fuel efficiency, so it would not be surprising to me that while driving in a non-ideal fashion (e.g., not allowing autostop to occur, braking in neutral or with the clutch in), the IMA system could possibly use more fuel than it saves.

[diamondlarry]

Originally Posted by aisbell

The IMA system is vital to make the whole package efficient and drivable under most conditions. An ICE is most efficient at low engine speeds (less frictional losses) and high throttle openings (less pumping losses), but such an engine is gutless pulling away from a stop up a slight incline with the A/C on. The IMA motor makes such situations tolerable.

I disagree with your assertion that the IMA system wastes more fuel than it saves. Without the IMA system, autostop, with its ~15% fuel savings in urban driving, would not be possible. Without the IMA system, energy could not be recaptured from braking. These fuel savings more than offset the addition fuel burned during regen if the IMA system is working well. We know that driving style greatly affects fuel efficiency, so it would not be surprising to me that while driving in a non-ideal fashion (e.g., not allowing autostop to occur, braking in neutral or with the clutch in), the IMA system could possibly use more fuel than it saves.

I do agree with the auto-stop benefits of the IMA. It is awesome to be able to sit at a light in total silence and then, just put the car in gear and pull away when the light turns green. However, as you mention driving style, my driving style makes IMA useful for the most part, only for auto-stop. As for recapturing energy in braking, my style means that for the most part, there is no energy to recapture as I'm usually very close to-and quite often under-the 12 mph threshold when I get to a stop because of heavy use of FAS. Though I have noticed that when the SoC is anywhere above 18 bars keeping the Calpod switch disengaged (in the car's stock mode) I get 5- 10 mpg better when I do drive in a steady state mode, for me the IMA is at best a wash when it comes to saving fuel since I spend so much time in FAS. Not sure exactly what's going on with the mpg increase when IMA/assist is enabled but it will probably be much clearer once I get my OBDII C&C installed. All that being said, since I'm significantly different than most drivers (ok, downright odd to most people), I'm more the exception and that for the average driver IMA probably does help save fuel.