Video: Can Skinnier Tires Increase Fuel Economy?

[cbergeron]

To be fair, I should mention that the larger wheels (aluminum rims) were actually heavier than the factory steel 13" wheels by about 8 pounds each.

Also, I found this calculator that will tell you how your speedo will misreport based on wheel size changes:
http://www.miata.net/garage/tirecalc.html
or:
http://www.miata.net/garage/tirecalcold.html

When I put had the larger 195 wheels on my car, my speedometer was slow by .02% (which I consider acceptable).

[MetroMPG]

Originally Posted by xtiago

Hi! this is my first post!

I found an article about how tire type can affect gas mileage (Honda Civic VX '95)

Hi, xtiago -

Good link. One of our Prius driving members documented a similar situation just this spring: http://forum.ecomodder.com/showthrea...ires#post11668

At first he saw a 10% decrease, which "improved" to just a 5% loss after a few 1000 miles.

Anyway, welcome to the site. If you're not shy, post a note in the "introductions" forum & tell us a bit about yourself.

-Darin

[Chris D.]

so when are you going to do a 4 donut setup for further testing..

You know your curious!

[cbergeron]

Ha, funny you should mention it...!

I was actually thinking about it this morning on my way in to work. My local junkyard just got another Aspire in stock today, so I'm going to head over there this weekend and get some. I think they're $10 each at my local yard, so this will be a $40 experiment, but it's for the greater good.

I'm a little hesitant about putting small wheels on the front, but I'll probably try it out anyway (at least one fill up) to see what happens.

I'll post my results as I make them happen...

[elhigh]

Originally Posted by HotRod

This is probably a totally dangerous/unfeasable option, but I was at the Lowes the other day and walked past their trailer tires. 12" just like the metro, but skinny, and a VERY high psi rating. ??? ummm...to bad they were a 5 lug.

I've been looking at that same thing - but my truck wears 5-lug, so it's feasible. They're cheaper than a set of Ranchos, look about the same, and come with a tire already on them! And a taller tire would correct my speedo, too. The VIN code says I've got the 3.73 rearend, but I think the speedo gear is for the 3.35.

Rather than replace the speedo gear for $10, I want to replace the rearend gear and slow the engine down at cruise. How's that for dedication?

[cbergeron]

Safety first - but that sounds like a great research idea. I looked at some trailer websites, but all of the wheels seem to be 5 lug.

Most of the wheels that I'd be interested in using are made overseas (so the shipping would be too expensive).

[RH77]

Originally Posted by trebuchet03

The only things that will change contact patch is a change in vehicle weight or a change in tire pressure.

Aren't do-nuts rated at 70-psi? Would that make the patch reduced?

RH77

[cbergeron]

I think tires should also be rated to include Total Air Capacity in addition to Pounds per Square Inch.

I tend to think that the more air in the tire at high temperatures and on a smaller hub yields higher MPGs when everything else is equivalent. I don't [yet] have any empirical evidence to base it on (other than my own experiments and observations).

[Chris D.]

any aftermarket lightweight wheels available in a 15x4? or 16x4 or so?

I want some skinnys.. I've be willing to run a 185-75-16 on my truck all around (if they make em)..

stock they were 205-75-15's

but I cant get anything narrower than that for mine..

[thebrad]

Originally Posted by Chris D.

any aftermarket lightweight wheels available in a 15x4? or 16x4 or so?

I want some skinnys.. I've be willing to run a 185-75-16 on my truck all around (if they make em)..

stock they were 205-75-15's

but I cant get anything narrower than that for mine..

5" is the lowest rim width I've seen unless you start looking at dead axle drag wheels, but those are just as inherently dangerous as donuts.