I have a 97 Civic EX and i was curious what kind of power gain or loss i would get from switching my wheels from 18 pound 14"s to 12 pound 15"s? I know you get some power gain from lighter wheels because you are losing un-sprung weight, but I also realize that if your tire is an inch bigger than your weight it farther away from the inside of the tire and slows you down more. What's the deal?

 

huh, you practically just answered urself. But one key thing to remember is morelike likely ur speedometer is gonan be off due to the size of the tires. From what I remember it was mentioned before in a different thread.

 

if his car and speedo are just like mine, the stock wheels and tires make the speedo about 3.5 mph too slow, going to 15s, and using the usual recommended size here, puts it bang on.

 

if the final diameter of rim+tire is the same even when going to bigger rims there won't be any change in acceleration... but you will gain some power from lighter wheels

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sohcpride &raquo;</TD></TR><TR><TD CLASS="quote">I have a 97 Civic EX and i was curious what kind of power gain or loss i would get from switching my wheels from 18 pound 14"s to 12 pound 15"s? I know you get some power gain from lighter wheels because you are losing un-sprung weight, but I also realize that if your tire is an inch bigger than your weight it farther away from the inside of the tire and slows you down more. What's the deal? </TD></TR></TABLE>


Yes you are correct with the less weight the less torque needed to turn the wheels. Also you are correct in saying the further out the weight is the more torque it will take to turn. In the end your shaving off so much more weight then the increase in size will effect your performance. If you got 17lb 15" rims then it may be close but worry more about weight then diameter.

 

diameter is important as well.. it's like saying that dx tranny and ex tranny are the same thing and you don't have to worry about it...same concept

 

the 15's will give you better acceleration, and don't worry about the speed difference. It'll be within 5% or so depending on the size tire you pick.