Just wondering how bigger rims will affect my 1/4 mile times, I know it will reduce acceleration but to what extent?

Lets say for example I have an Integra GS that's running 16.0 on stock Alloy rims, if I swapped on a set of 20lb 17's what would my 1/4 mile time be?

 

If you properly plus sized your wheel/tire combo so that the tire diameter is that same as before and the weight of the new set-up is less than or equal to the weight of your old set-up there should be no loss in the 1/4 mile.

 

Not sure, but I went from a 15" wheel that weighed 16lbs to a 15" wheel that weighs a little less than 12 lbs, and I noticed a significant difference in acceleration.

 

ok well I'm getting some Enkei RS6's they're about 20lbs, i think that's about 5lbs heavier than stock.

stock = 7" radius + 4.68" rubber (195/60) = 11.68"
17's = 8.5" radius + 3.28" rubber (205/40) = 11.78"

so pretty damn close in the overall diameter, so it's just the weight then, how much will the 5lbs affect my times??

 

I cant give you a number, but think about this

what you are fighting is not just the weight itself, but the location of the weight. I'm not going to dig up my old physics book to get the calculations, but 20lbs is not 20lbs. a 15in rim that weighs 20 lbs will still accelerate faster than a 17in rim that weighs 20 lbs, becasue the weight is closer to the center.

 

ya I'm looking for actual numbers, real-life experience with different rims.

I know what you mean by 20lbs not being 20lbs, but it seems to me that the overall diameter of the 2 tires would be almost equal, but ya I can see there's more to the equation than overall diameter and weight.

I think all this theory's worthless though, I need numbers!


[Modified by 2chron4u, 2:25 AM 2/12/2003]

 

is it better to have the weight at the center of the rim, or the perimeter of the rim?

 

generally the concentration of the mass closer to the center of the wheel is more desirable than the perimeter. on the contrary to someone saying that it is detrimental to acceleration.
due to centrifugal forces, any mass further away from the center will experience more drastic increase of weight. imagine being on a merry-go-round. for example. if you stand close to the center of it, you will feel relatively small amount of G-forces applied to you by the centrifugal forces of the spin. if you stand on the edge, on the other hand, you will have to hang on pretty tight, even at relatively slow rotation.
the only adverse effects from going 15 heavy to 17 light wheel, provided they both yield same mass total, is the placement of heavier 17 tyre.
stan


[Modified by 90crxsi, 7:08 PM 2/11/2003]

 

wow, that is a lot info. thanks

 

i forgot to add the important thing that all this leads to, momentum, the further away from center your mass is the more momentum it has, hence, more time to get that wheel spinning.
stan

 

All this gets back to inertia. The more inertia a body has the greater its resistance to acceleration and deceleration. You can use this formula to roughly figure it out: moment of Inertia =mass*radius^2. As you can see, the radius plays a larger role in the amount of interia than overall mass does. Double your radius, get four times the inertia even if mass stays the same. I know nobody will actually double the radius of their rim, but you get my point.

Alin

 

so no-one can give me some real life numbers on the affect of going from 15lb 14" rims to 20lb 17" rims.

Would I lose .1 or .2 seconds, or would it be worse than that?

 

sir you are correct. i remember that from last sem physics..

 

some one once explained it by saying.. take a weight and tie it to a string. Start with the string being short and beginning spinning it around likea wheel... this will be easy to get it going, and keep it going.

Now stop and extend the string and try again. It takes more effort and energy to start the "wheel" with the radius of the circle being larger.

 

I have actually seen up to .5
but they went from a 14" stock rim to a 18" bling bling rim..

We plan to test this in the spring, and will post the results on our website.

 

i know there are lots of factors... but at the strip on sunday. 2 turbo jettas. one with stock 15's and other with some bling 17's.. well the 15's won by a good amount. i know there is some driver error involved. but i saw plenty of 17" cars out there going slowwwwwwwwwwww.. no wait. those were only civics.. lol

 

I have had stock 15s, Work RS Beta's 15s also and approx 11/12lbs, JDM sparco 16" rims (13/14lbs) and the current BK102s (17lbs) 17s on my integra and TBH i didnt notice any difference in acceleration either low down or higher up, time slips may have shown slight differences, but seeing as i dont drag my car very often i have never been able to tell for definite