"Rolling Resistance"

[ihslave]

Hey all,

I have been noticing the term "rolling resistance" on this site a lot lately... seems to refer to the concept that a wide tire drags the efficiency of being propelled down the road as compared to a skinny tire.

It sounds good to me, but I have also noticed for several years now that a lot of big rigs have been converting from dually tires on their trailers to one large tire that takes up the same space. A couple of quick measurements has shown that the surface area of the single tire is greater than that of the two standards added together.

Truckers tell me this setup saves them around 10-15% fuel over long hauls... which seems opposite of the "rolling resistance" concept.

Just curious to see if anyone has an explanation on that?

scott

 

[rlireland]

As with most topics and questions, the Internet is a vast souce of information.
Here's a site that explains rolling resistance for truck tires (tyres for those Down Under).
My theory on the wide vs narrow truck tires is that it probably has more to do with load distribution and tire wear and replacement cost than with fuel economy. Of course the higher diesel prices go, the more this may change. We might see the trend go back to narrower tires.

Roy

 

[Mt Hood Carl]

I would guess the biggest contributor to rolling resistance is the energy it takes to continually deform the tire as it rolls. And it makes sense that it takes less energy to deform two sidewalls than four sidewalls.

 

[jeepdaddy2000]

The savings isn't so much from resistance as weight savings. A "super single" with an alloy rim weighs considerably less than two tires mounted on steel rims. We tested these briefly at work, however, since our trucks are susceptible to flats, the singles were more trouble than they were worth.