Quote:
Originally Posted by NeilBlanchard
Hi,
Thanks Doax! I added the items I had modded to the post above.
How can one measure the rolling resistance of their tires as they are inflated on their car?
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I don't see how to measure ONLY the rolling resistance, but you could measure the non-aerodynamic resistance just by using a force gauge to push or pull the car at VERY low speed (barely moving) in neutral. Aero drag would be negligible so if your car weighs, say, 2400 pounds and it takes 36 pounds to push it, your overall "mu" (Crr) would be 0.015. Obviously, this includes tires plus friction in everything behind the transmission. You'd want to get it to a steady (SLOW) speed so the kinetic energies (linear and rotational) are constant. Also, though a dimensional analysis shows that, to first order effects, tire rolling resistance depends only on down force (weight plus aerodynamic) and not obviously on speed, unfortunately aerodynamic down force depends on speed.
You can come reasonably close to the weight of the car with an accurate tire pressure gauge, two pieces of paper, and a machinist's scale. I think that's been covered in Ecomodder so, unless there's a demand, I won't waste time by repeating the method. The key here is the accuracy of the gauge - the typical pocket gauge may be off by a wide margin.