Quote:
Originally Posted by elhigh
I don't agree that rolling resistance is a bigger issue, though it's pretty obvious that with 18 wheels, there's a heck of a lot more rolling resistance on a truck than a car. Add a full load and it gets worse.
My understanding is that rolling resistance increases as a linear progression, but aero is a exponential progression. So the rolling load increases, but not as fast as aero drag does.
|
I forgot where I read the rolling resistance information, but it depends heavily on speed. Any trucker doing the legal limit (55mph) and not fighting a headwind/crosswind, will see most of his fuel being spent on rolling resistance...especially when brand new tires are fitted. Above 55mph, drag starts shooting up immensely dur to air drags exponential rise (as you've noted).
Again, I've forgotten the exact penalty truckers pay for speeding slightly (~5mph), but I remember it being fairly immense (~25% FE hit, I believe). At 55mph, air drag is a major source of drag...but I am pretty sure it is not the overwhelming source. Ofcourse, lowering it will still help immensely...but the point is that rolling resistance is a big deal in the trucking industry.
- LostCause