wheel vs. tire weight ratio

[Alastor187]

Originally Posted by GreyGoose006

as for the moment of inertia, i dont really think it is as big a consideration as weight because the wheels are all of the same design and the tires are all made by the same manufacturer.
its not like i am trying to compare two different wheel sizes and styles at the same time...

It is a big deal because the rotational moment of inertia is related to the wheel radius raised to the 4th power. So even modest changes in tire diameter can have large affects on MofI.

As for the optimization of the wheel and tire, I think it could certainly be done to include both weight and MofI.

However, for most cases the trend is that a smaller tire/wheel combination will yield a lighter assembly with a lower rotational moment of inertia. The leading constraint becomes clearing the brakes. So the best overall solution is the smallest tire/wheel that clears the brake calipers.

[GreyGoose006]

Originally Posted by curtis73

Assuming this:

-keeping same overall diameter and section width
-increasing wheel diameter

You almost always increase overall weight. The answer to your question (which seems to have been missed ) is that you add weight with the larger wheel, AND you add weight with the lower aspect ratio tire. It sounds backwards, but less tire usually means more weight. In order for the tire to maintain its roundness and weight capacity, there is often times more material required in both the tread area and sidwalls.

For instance, if you compare a 275/40-17 and a 275/30-20 tire, the 20" tire will almost always be heavier, even though it is the same overall diameter.

Judicious selection of brands, styles, and tires can net you a minimal gain in weight, but among the same brands and models, bigger wheels = more weight for the same diameter.

now thats an answer that i like.
not telling me that i'm dumb for wanting to know...

thank you.


it does seem to make sense that a lower profile tire would weigh more now i guess.
i guess you have to find the lightest and biggest wheel you can so that brakes will fit and you can keep the light weight.

either way, anything is better than the hugely heavy stock steel wheels.

[curtis73]

If you're set on one wheel and/or tire type, you'll have to choose a size/weight that fits your purpose, making a trade-off between looks and performance. Often times you can add size without too much penalty if you're willing to compromise on price and/or style.

I was able to lose weight on a BMW E30 when going from stock 14" to aftermarket 16". I was able to find lighter wheels and tires that weighed the same, but it wasn't cheap. $1600 for the wheels and $800 for the tires. Then I ended up selling them when I started running consistently better times on 15s.

[drunken monkey]

Originally Posted by curtis73

I was able to lose weight on a BMW E30 when going from stock 14" to aftermarket 16". I was able to find lighter wheels and tires that weighed the same, but it wasn't cheap. $1600 for the wheels and $800 for the tires. Then I ended up selling them when I started running consistently better times on 15s.

and that was why i said it was a pointless question.
having the lightest wheel/tyre combo doesn't always mean having the best performing tyre/wheel.
As he also said in the previous post, to maintain the use of the tyre, there is often more mass in the tyre. This means that the behaviour of each tyre as you get a narrower sidewall is going to be very different again, affecting what is "optimum".