Using Honda Insight spares with RE92s
 

Hi,

I was wondering whether it would be possible to use spare wheels from Honda Insight with RE92 165 profile. Insight spare wheel is 4" wide and I think 165 tire should mount without any problems.
Thank you.

I asked that question here: http://ecomodder.com/forum/showthrea...tml#post115739

and our resident tire geek told me why it wouldn't work.

Considering the number of gently crashed Insights with broken wheels, Honda made the full size wheels thinner than usual, and I'm sure the spares are more so.

If only they made a LRR tire in a more reasonable width, like 125mm wide.

Thank you for a link, but I didn't read "won't work", he was saying that narrow wheel will not decreasing rolling resistance. I'm after weight saving with insight spare rim. Decreased handling is not a big problem since using
165s implies no handling anyway.

why wouldn't a narrower wheel decrease rolling resistance? a narrower wheel should squeeze the tyre to be a bit narrower as well, which would slightly reduce the width of the contact patch.
going to narrower tyres and wheels works beautifully to reduce rolling resistance on bicycles, motorcycles, atv's, wheelbarrow's, etc... all of which I have personal experience with.

so why wouldn't it work to decrease rolling resistance on a car? When my current tyres wear out, I had planned on replacing them with skinnier tyres.
Stock is: 195/65-15
My current ones are: 215/60-16
I want to put on: 185/70-16 to 185/60-16 or there abouts.

My car's computer controls the speedometer, and I can reprogram the computer to accurately reflect real vehicle speeds if i change the tyre hight or diameter. Most vehicles esp older ones had non adjustable speedo's or even mechanical ones with a spinning cable. mine is completely adjustable via software so changing my tyre size will not be a problem as far as speedo accuracy goes.

I would imagine it has to do with the deformation of the tire. As you narrow the contact patch it must expand due to the increased load per sq/area. This means it has to grow longer. Longer means the tire itself is going to need to deform more while rotating.

Oh? Ever driven an Insight? It handles way better than most.

i understand completely but it seems to me that having a wide tyre would result in a contact patch that is wider, but not very long. where as having a skinny tyre would result in a contact patch that is not wide, but skinny. and because of this the contact patch would have to be longer to make up for it.

so what is better, a wide but short patch as is on a wide tyre,

or

a skinny but long contact patch as is on a skinny tyre,

what would result in lower rolling resistance? i would bet the overall square inches of the contact patch would be the same no matter if the contact patch was wide and short or skinny and long. because the tyre needs a certain amount of area touching the road for a given weight being placed on it by the vehicle.

since bicycles and all the other things i mentioned greatly benefit from skinny tyres with longer patches, why wouldn't this same logic work on a car?

does anyone have examples of some oem car that has better or worse fuel economy when using wide tyres vs skinny ones?

i do know that virtually anywhere that rolling resistance is a major factor, skinny tyres are used. even downhill soapbox cars with no engines that rely on gravity. those also use skinny tyres.

i could be wrong as i am only guessing at all of this, but why wont it work on a car....

Bicycles do NOT benefit greatly from skinnier tires!

In and of itself...

It has to do with the load the tire sees, the pressure run, and a host of other things too...

But I have personally experienced much EASIER pedalling with wider bicycle tires.

There are tires threads here already which explain the mechanics of rolling resistance.

Suffice to say, narrower is not always better.