Hi,

I picked up the following graphs from:
Tire inflation lookup table:
Speed lookup table:Vehicle drag is a function of rolling resistance and drag times the velocity squared. However, tire rolling resistance is not a linear function with speed and these charts give a clue.

Bob Wilson

 

Interesting graphs. I've thought that keeping my tire pressure at 40 psi was getting the most out of the inflation/mileage curve, but your first graph shows that rolling resistance is still dropping at 90 psi!

The second graph confirms my belief that speeds above 55mph should be avoided.

 

Very interesting

 

Here's a link to a site with a report on LRR tires. There a PDF with the article and some data.


http://www.treehugger.com/files/2005...olling_res.php

 

Thanks for the helpful information, I never knew that one before... Thanks Again!!!

__________________________
Ever heard the name Pulstar Plugs ???

 

Here is another link that has a ton of presentations about TRR. The presentation by Chris Calwell is especially interesting. He has some graphs showing the impact of tire pressure versus fuel economy on a group of unspecified tires for urban and highway driving (pg16 & 17).

IEA - Energy Efficient Tyres: Improving the On-Road Performance of Motor Vehicles

Empirical analysis of rolling resistance and performance trade-offs - Chris Calwell (Ecos Consulting, USA)

 

As a percentage of rolling resistance reduction, it appears that 36 psi in the tires is ideal, and 60 mph maximum cruise speed also appears to be best.

 

Thanks for the info. It does appear that 40psi is probably the best pressure to use, depending on your preferences of course. That's what i have been using for almost a year now. I'm happy with the Michelin MXVS tires i have now. They seem to be working well and will last for at least 4 years.

 

A low-rolling-resistance tire is a tire that generates less friction with the road surface than a normal tire, which helps improve fuel economy. Buying low-rolling-resistance tires reduces petroleum consumption and emissions from your vehicle.
_______________________________
Check out: Autopartswarehouse.com

 

WRONG! The tread to surface friction has almost nothing to do with the design of a Low Rolling Resistance (LRR) tire. This incorrect conclusion also contributes to the fiction that an LRR tire is not as safe as non-LRR radial tires. NOT TRUE, in some cases an LRR tire, because of its high technology sidewall may have a higher tread to surface coefficient of friction.

The decrease in rolling resistance in an LRR tire comes almost completely from a reduction in the amount of energy required to force the distortion of the sidewall when the tread begins to come into contact with the road surface. You can think of it sort of like the car is pushing a "wave" of compounded rubber ahead of the point where the tire begins to contact the road. The advanced rubber compounds used in an LRR tire requires less enegy to push this "wave" becasue it is smaller, i.e. less energy is requied to accomplish the sidewall distortion.

The decreased energy required results in better FE and less tire heat. As counter intuitive as it is, the more flexible sidewall can also result in the tread having better contact with the road. This is becasue the sidewall transfers less cross-ply distortion onto the tread, which reduces cupping or twisting in the tread.

The Michelin website has an excellent and entertaining video on the theory behind LRR tires. Link = http://www.michelin-green-meter.com/main.php?cLang=en.