Mostly musing here, but I would be interested in your thoughts. Since our front tires do almost all the work: steering, power and the vast majority of the braking force, it seems changing things in back might yield some real gains with minimal losses. There have been several threads talking about drastic over inflation, and narrower tires etc, but I hate to see safety and performance compromised. What are your thoughts about narrower, higher pressure tires in the rear only. This could reduce mass (rotating mass at that), reduce rolling resistance and perhaps even accommodate wind cheating wheel skirts.

Your thoughts?

 

so what ur trying to do is turn the fit into a 4-door insight?

 

Must admit, I don't know the Insight that well, but from what I have seen I suspect there are some other advantages of the Fit beyond 2 more doors. Also, I made no suggestion of Hybridizing the Fit (though others have discussed it). Nonetheless, if these concepts were used beneficially on the Insight, couldn't they benefit efficiency oriented Fit drivers as well?

 

I suppose you could use thinner tires to reduce resistance, visually the skit idea is going to look very strange.

 

That would be great! I love the Insight. I almost bought a brand new one about 7 years ago... I should have.

Perhaps covering the fender wells would work. (Check out Ecomodder.com Fuel Economy Forum).

Let me know the results if you decide to do it.

 

I recently discovered Ecomodder and I love visiting the site.

An ecomodder tried an A-B-A experiment using skinny tires in the back.
He made a video of it:
Video: Can Skinnier Tires Increase Fuel Economy? - Ecomodder.com Fuel Economy Forum

Summary:
Normal tires: 56.9 mpg
Skinny tires: 60.9 mpg
Normal tires: 54.9 mpg

So ~8.9% improvement.
The skinny tires he used looked sketchy and were rated at 50mph max.

I have never been in the market for tires and have not researched them enough, but I would consider getting something that was a little less narrow.

 

Nice site. A quick glance had little specific for a Fit. I'll search more tonight. I was thinking of the tire change a few months ago but was surprised at the gains.

Anyone want to lend me your Fit spare tire?

I'l in LAke Worth near West Palm

I would need 3 for 2 weeks to make a good A-B-A test and post the results.

Funny how the Fit has very little in the way of documented or bolt on stuff to help Eco.

 

inflatting your tires to the tiremaker's recomendation is not unsafe. the car makers always recommend lower pressures because it makes for a nice comfy ride (which the averge person translates into "good car").
I also find that my Fit handles better with the higher pressure (especially in the rear), although it is a rougher ride for sure.
Tirerack says (or at least it used to) that the stock Fit tires are LRR tires.

As for aurodynamic gains, i suppose skirts could possibly make some (very small) difference, but the real problem is the huge blunt rear end.

 

Nice link, thanks. Looks like the tires in rear make quite a difference.

Psc0snq: Hope someone close by loans you their spare, would love to see those results.

Sortanewinatl: Safety wise, I am not so concerned about the tires themselves failing at or near the manufacturers rated pressures, but I still think there are some safety issues with running very high pressures, especially on the front of front drive cars. The very thing that gives the eco advantage (essentially less contact with the road) can also mean less grip when you need it for braking or maneuvering.

Cheers all, and thanks for the comments so far.

 

actually, it's not less contact with the road that gives the eco advantage there.... i have 48lbs in my rear tires (rated for 50lb) and they are not stretched, bowed, or distorted out of shape in any way... the contact patch is the same as it was at 30lb, and probably would still be the same at 20lb.
the advantage comes from the side walls... they don't sag (as much), so the engine doesn't have to "lift" the car as it rolls.