Originally Posted by t(ack)oma
anyone know if smaller, unaggressive tires would lower the vehicle enough to make a differance? i know the overall air displacement as the truck moves is a major factor in fuel economy. good luck! i'll let you know what i find out, too
The drag effect on the truck is substantial. I've been driving a Subaru WRX--not a particularly streamlined AWD car--for four years, and I noticed it immediately in my 07 2WD Prerunner. I can coast down an exit ramp and strongly decel just from air resistance, even in neutral...compared to the WRX, where I'm downshifting and braking, and dealing the AWD drivetrain drag, too.
tire/wheel combos will help mileage and acceleration. OTOH, if you do a lot of interstate speed driving, larger diameter
tires can give sort of an overdrive effect, lowering your RPMs at speed...how much either would help I can't say, but I'd bet the lighter wheel/tire set up would be the more effective.
On the aerodynamic angle...can bug deflectors improve the aerodynamicity (is that a word?
) of the vehicle? They get the air moving up over the windshield...so they're simulating (as far as the airflow is concerned) a more angular, wedge-shaped vehicle, as opposed to a "box (cab) on top of a box (hood/engine compartment)".