Down Sizing

[BEEF]

Just because it is an inch smaller in diameter doesn't automatically mean it will weigh less. If you went from a lightweight aluminum wheel to a steelie, it could very well weigh more.

Making your wheels smaller (overall diameter of the wheel/tire) is the equivalent of increasing your gearing and thus giving you more torque but at the cost of lower top speed and thus making your motor turn a higher RPM for a given speed.

I was thinking of changing the gearing on a pickup truck that I had (for acceleration). I was going to go from 3.55s to 4.10s. I was told to get a feel for what it would be like, I should swap out my wheels from the stock 29.5s to 26 inch racing tires (those are overall diameter). I ended up just swapping the gears and the acceleration and takeoff were awesome... I lost about 3mpg in the process.

If you are using 14" wheels with meatier tires where the overall diameter is the same as the 15s, then disregard all that I have said. you would get weight savings with that only.

[Flipper_1938]

Originally Posted by BEEF

If you are using 14" wheels with meatier tires where the overall diameter is the same as the 15s, then disregard all that I have said. you would get weight savings with that only.

Not exactly.

Even if the weight is the same, there could be a difference in rotational inertia. The 14" wheel will have the mass of the rim closer to the center of the wheel and will therefore require less effort to accelerate.

The 20's on the truck in my icon hurt acceleration fiercely, but they look cool.