Power loss with 20's?
12-04-2006, 12:55 AM
#81
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Join Date: Oct 2006
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Posts: 1,111
RE: Power loss with 20's? here we go again!
The extra weight could slow you down but you just have to decide if you want to look good or take a little power hit ..... if your going to run it at the track every w.e. i wouldnt put 20s on but if your just an occasional dragger then go ahead and slap them on it wont be a huge difference
12-04-2006, 01:08 AM
#82
2nd Gear Member
Join Date: Sep 2006
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Posts: 184
RE: Power loss with 20's? here we go again!
my 20" wheels & tire combo weighs 11 lbs more per wheel, I know because a friend loaned me his stock wheel & tires when I took one of mine in to the chrome shop for replating. While we had the 1st wheel off we weighed it and found the difference - don't remember the exact weight, just that the 20's were 11 lbs heavier[
]
Don't care though, this isn't a racecar, its a streetrod that is as much about looks as performance and just plain old old fashion streetfun
]Don't care though, this isn't a racecar, its a streetrod that is as much about looks as performance and just plain old old fashion streetfun
12-04-2006, 05:37 AM
#84
I ♥ Acer
Join Date: Aug 2006
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Posts: 2,090
RE: Power loss with 20's? here we go again!
ORIGINAL: GrabberOrange07
I agree with some of what you are saying about weight and sidewall flex but the radius on the tires will remain the same. Thats why you have a small sidewall. I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
ORIGINAL: androdz
20's Hurt you performance because:
1. There is less sidewall to actually bend during launches so that the tire doesn't put all the power in one woop to the ground but a more progressive (Look at a dragster wheel, the rim turns almost 1/2 way before the tire starts moving)
2. Most 20's are made for looks and not performance thus they tend to weight more which this in turn means more rotational weight and approx 1lb rotational = 4lb regular weight
3. Since they have less sidewall and tend to weight more and have a bigger radius that means the weight is more concentrated farther from the center of the wheel which this in turns makes it harder to turn.
I am trying to get a friend of mine to our local dyno to prove the actual hp loss on stock 17's vs 20's. Of course I am gonna weight his 20's so you guys get an idea of the 20's weight.
Att. Andrew
20's Hurt you performance because:
1. There is less sidewall to actually bend during launches so that the tire doesn't put all the power in one woop to the ground but a more progressive (Look at a dragster wheel, the rim turns almost 1/2 way before the tire starts moving)
2. Most 20's are made for looks and not performance thus they tend to weight more which this in turn means more rotational weight and approx 1lb rotational = 4lb regular weight
3. Since they have less sidewall and tend to weight more and have a bigger radius that means the weight is more concentrated farther from the center of the wheel which this in turns makes it harder to turn.
I am trying to get a friend of mine to our local dyno to prove the actual hp loss on stock 17's vs 20's. Of course I am gonna weight his 20's so you guys get an idea of the 20's weight.
Att. Andrew
I agree with some of what you are saying about weight and sidewall flex but the radius on the tires will remain the same. Thats why you have a small sidewall. I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
Att. Andrew
12-04-2006, 07:03 AM
#85
6th Gear Member
Join Date: Sep 2006
Location: Gainesville, FL
Posts: 11,278
RE: Power loss with 20's? here we go again!
ORIGINAL: GrabberOrange07
I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
12-04-2006, 07:06 AM
#86
5th Gear Member
Join Date: Mar 2006
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Posts: 3,758
RE: Power loss with 20's? here we go again!
ORIGINAL: moosestang
It's not the same kind of weight. The engine doesn't have to turn the fuel tank or your passengers.
ORIGINAL: GrabberOrange07
I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
12-04-2006, 10:45 AM
#87
5th Gear Member
Join Date: Mar 2006
Location:
Posts: 2,544
RE: Power loss with 20's? here we go again!
ORIGINAL: GrabberOrange07
I agree with some of what you are saying about weight and sidewall flex but the radius on the tires will remain the same. Thats why you have a small sidewall. I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
I agree with some of what you are saying about weight and sidewall flex but the radius on the tires will remain the same. Thats why you have a small sidewall. I think the weight thing plays an important roll in performance and the fact the 20" combo does weigh much more than 17's or 18's does rob power but so does a full tank of fuel and passengers. Just have to pick your battles.
Wheel weight isn't the whole story. The real problem is the INERTIA of the wheel. Inertia is calculated by integrating mass times radius over the entire wheel. Remember calculus class back in school?
Anyway, the point is that if you have two rotating objects of identical weight, but one of them is larger in diameter than the other one, the one with larger diameter has more inertia. This is a classic phyics demonstration that you might have seen in school: a larger hollow ring has more inertia than a solid disc, even though both weigh the same.
In other words, suppose you had two wheels, both of which weigh exactly 25 lbs on a scale. Their designs are identical except for the diameter: one of them is an 18" wheel and the other is a 20" wheel. The 20" wheel has more inertia becasue it has a larger radius, despite the fact that their weights are identical. More inertia = bad for performance.
Not only do most 20s weigh more than the smaller wheels, but they also carry the bulk of that weight at a larger radius than their smaller counterparts. Thus even if the 20" wheel weighs the same as the smaller wheel, it's inertia will still be higher simply becasue it is larger.
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