I do a bit of biking as my other hobby, and wheel and tire weight is massively important to handling, acceleration, and deceleration in biking. It this the same with cars?

At first I thought "duh, of course, less rotating mass means faster acceleration" but then I thought about how the axels are also rotating mass, and for that matter, the whole drivetrain is rotating mass that is connected to the wheels, therefore making the difference in the weight from one wheel and tire combo to another negligible.

Is my logic sound in this case or am I way off? :confused:

You are dead on! The lighter the better, talk to the guys that arer running heavy 20" wheels and how much power it takes to move them quickly.

The trick is to keep the weight as low as possible and keep it at the center of the rotation.

The other trick is to have the wheels and tire storng enought to supprt the weight sitting on them! :D

That is why light drag wheels bend easy on the street.

-Bobby-

Yes weight is a big factor. I've heard 10# off rotating mass is equal to 100# of static weight.

A buddy of mine that used to bracket race named a ratio, something like lose "x" amount of rotating weight, drop "y" amount of time at the traps. I'll buy that, it makes sense.

Here's my question though. There is a method for calculating horsepower from a time slip, if you know your vehicle weight. The factors are E.T., trap speed, tire height, and vehicle weight. Does that mean that if you were to drop say 20 lbs from switching to aluminum wheels, that one could argue that it equates to a horsepower gain?

A buddy of mine that used to bracket race named a ratio, something like lose "x" amount of rotating weight, drop "y" amount of time at the traps. I'll buy that, it makes sense.

Here's my question though. There is a method for calculating horsepower from a time slip, if you know your vehicle weight. The factors are E.T., trap speed, tire height, and vehicle weight. Does that mean that if you were to drop say 20 lbs from switching to aluminum wheels, that one could argue that it equates to a horsepower gain?
any mass you remove from the car frees up power- rotating mass especially. the more mass you have in a wheel and tire, and the farther out it is from center, the harder the motor will have to work to overcome it's inertia. and a heavy wheel will require the springs and shocks to work harder to dampen it's movement when it hits a bump.

I do a bit of biking as my other hobby, and wheel and tire weight is massively important to handling, acceleration, and deceleration in biking. It this the same with cars?

At first I thought "duh, of course, less rotating mass means faster acceleration" but then I thought about how the axels are also rotating mass, and for that matter, the whole drivetrain is rotating mass that is connected to the wheels, therefore making the difference in the weight from one wheel and tire combo to another negligible.

Is my logic sound in this case or am I way off? :confused:
Luke. Its not only rotating mass but "inertia". Where the mass is located. The mass of a axle or drive shaft is very close to center so it takes less force to spin it. In the same context. A 20" wheel that weighs 20lbs will take more force to spin than a 14" wheel that weighs 25lbs because the mass is farther from the center.
A buddy of mine that used to bracket race named a ratio, something like lose "x" amount of rotating weight, drop "y" amount of time at the traps. I'll buy that, it makes sense.

Here's my question though. There is a method for calculating horsepower from a time slip, if you know your vehicle weight. The factors are E.T., trap speed, tire height, and vehicle weight. Does that mean that if you were to drop say 20 lbs from switching to aluminum wheels, that one could argue that it equates to a horsepower gain?
Jake, It won't gain "engine HP" but it will effect "Net" or rear wheel HP. The less mass an engine has to spin, The more of its "gross HP" reaches the ground.

Thanks Scott. :beers: Makes perfect sense that way.