List of Coefficient of Rolling Friction for name brand tires???
List of Coefficient of Rolling Friction for name brand tires???
(OP)
I am having a hard time finding any information on the rolling resistance of car tires. I am working toward increased fuel economy but the manufacturers will not answer the questions I am asking, namely what is the CRF (coefficient of Rolling resistance) of certain size tires they manufacture, Anybody have access to test data for car tires???
Gary M&G Engineering
Gary M&G Engineering





RE: List of Coefficient of Rolling Friction for name brand tires???
They may be able to provide specific numbers if contacted directly, I don't know.
Hope this helps.
Jason
RE: List of Coefficient of Rolling Friction for name brand tires???
gpara
RE: List of Coefficient of Rolling Friction for name brand tires???
It's been estimated that tires contribute about 17% to the fuel consumption of a vehicle. That means if the rolling resistance changes by 20% (which is a huge improvement!), then this results in a 3.4% change in fuel economy. In a 30 mpg vehicle this would be 1 mpg. I don't think this is significant especially considering that inflation pressure can have the same effect.
RE: List of Coefficient of Rolling Friction for name brand tires???
Typical rolling resistance for car tires varies from 0.0110 to 0.0150, on smooth road, and truck tire might be as low as 0.006, and I have seen experimental tires as low as 0.0025. A good bicycle tire might be around 0.0055 .
So a 20% change is not all that difficult to get. Your 17% sounds about right.
When we specify tires we do include rolling resistance, it does make a measurable difference to fuel economy.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: List of Coefficient of Rolling Friction for name brand tires???
If the range for car tires is 0.110 to 0.150, then that's a bit over 30%, but I'll bet that includes tires that have different design goals - traction vs rolling resistance vs wear. Perhaps some speed rating differences, too. If you compared similar tires, I think you'll find the differences aren't that great, especially compared to the difference you can get with inflation on the same tire.
RE: List of Coefficient of Rolling Friction for name brand tires???
Regards
eng-tips, by professional engineers for professional engineers
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RE: List of Coefficient of Rolling Friction for name brand tires???
Admittedly I think this is more of an 80 psi problem than 40, but it is something to think about.
According to another piece of paper, increasing the tire pressure by 10% should reduce the rolling resistance by 6%
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: List of Coefficient of Rolling Friction for name brand tires???
has some interesting data. size for size there is much more than 20% difference between tires.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: List of Coefficient of Rolling Friction for name brand tires???
But if you look carefully you'll see that only the 185/70R14 size has data outside the 20% range and the only tire in that size outside the 20% range is the Bridgestone B381, which I believe is the tire on the Prius (a hybrid) and there seems to be universal agreement that the tire delivers good fuel economy, but is FAR from acceptable for traction and wear.
RE: List of Coefficient of Rolling Friction for name brand tires???
RE: List of Coefficient of Rolling Friction for name brand tires???
I did a fuel economy exercise in the early 80's. Part of this project included tires. I originally had a set of Goodyear belted (non-radial) snow tires (4) on a truck and after switching to a set of Goodyear Tiempo radials, I saw no significant difference in MPG. That surprised me with all the hype on radial tire fuel efficiency. I used a Zemco computer to measure data.
PS
RE: List of Coefficient of Rolling Friction for name brand tires???
I have finally broken in the Falken ZE 512 tires, about 5000 miles on them. Unfortunately they have NOT given me any more fuel economy than the original OEM tires. They were Bridgestone B450, SR rated, just a cheap OEM tire.
These new tires are directional in rotation and have a max tire pressure of 55psi. I have been running them at 48psi and there is no noticeble difference in coasting or fuel economy.I have checked it under varing conditions, I am disappointed that there was NO difference. Any commens????
PS I am waiting for Hydrogen generator, electrolisys, that will produce 1L./minute at 15amps, that should really boost the economy.
Gary
RE: List of Coefficient of Rolling Friction for name brand tires???
With most tires, the older they get the stiffer or harder they get. That's why new tires are gripier, smoother, and quieter. Even if you put back the exact same make and model tire, but new, you would likely be similarly disappointed in mileage. Time to move on to hydrogen.
RE: List of Coefficient of Rolling Friction for name brand tires???
Unfortunately, if you walk into a tire store and buy the 'same' tire, you may not get the same tire.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: List of Coefficient of Rolling Friction for name brand tires???
A tire's rolling resistance changes as the tread wears away. A better way to look at this is that tire weight - especially tread weight - adversely affects rolling resistance. So a brand new tire will consume more fuel than the same tire when the tread is nearly worn out.
So comparing 2 tires on a vehicle - one new, one worn - doesn't tell you much about the difference in the tires.
Also, inflation pressure has more of an effect on rolling resistance that the difference between tires. So if one is interested in reducing costs, one is probably further ahead getting a long wearing, but high rolling resistance tire and using more inflation pressure. The downside to this is that there will probably be some reduction in dry grip (and under certain circumstances, wet grip, too!)
Hope this helps
RE: List of Coefficient of Rolling Friction for name brand tires???
2006 Hyundai Tiburon V6 with Firestone Wide Oval performance tires 215/45R17 87W with 4000 miles wear 30.0 psi cold.
Warm up 3 miles. Ambient 86°F Cruse control speed set at 63.4 mph checked with Garmin GPS.
Fill gas tank using slowest fill speed and automatic shut off. Gallons measured to 0.001 Gal
54 mile loop on Interstate 76 East of Akron
Refill gas using same pump, same procedure for shutoff etc.
Test A 34.45 mpg Windows open no AC
Test B 32.93 mpg Windows closes AC on ~ 5% worse
37 yrs Tire Eng. Designed basic rain Firestone for CART. SCCA & IMSA Pro & Am. Set lap records at 6 different road courses in '89-91.
RE: List of Coefficient of Rolling Friction for name brand tires???
Gary