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Old 12th April 2005, 12:16   #1
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Default new tires:FE up or FEdown????

guys,

when tires get worn off,the traction offered by these worn tires decrease with every km.
as a result the grip offered will also be lesser.
so theoretically,the FE should increase .

and when u fit new tires of the same size,the grip offered is better .which should mean lesser FE due to improved traction.


but we see everyone saying that their FE has improved after fitiing new tires of the same size.


is this possible????????


satya
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Old 12th April 2005, 13:14   #2
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on the contrary satya, F.E actually decreases due to worn tyres, as worn tyres have smaller circumference, due to which the overall rolling distance decreases, thus resulting in decreased efficiency;plus, the worn tyres mean that while driving on highways, the traction decreases, and the slip between the tyre and the road increases-meaning the engine has to rev more to produce the same speeds, as against new tyres.

all the same, your in city or low speed (say, upto 40-45 km/h) F.E should go up slightly, as the engine has lesser friction from the tyres to cope up with, which means lesser resistance to move the car.

new tyres definitely aid in the overall dynamics of the car, not to mention grip, cornering abilities, and overall F.E.

but it also depends upon which tyre size you go in for; if you're running stock tyres of, say,165/70 R13, your F.E., ride quality, and handling will increase if you go in for 185/70 R13; also, if you go in for 185/65, you'll get better handling as compared to both the said tyres, but F.E. will be lesser than the 70 profile (185); also, you'll get lesser ride quality.
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Old 12th April 2005, 13:21   #3
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Quote:
Originally Posted by veyron1
as worn tyres have smaller circumference, due to which the overall rolling distance decreases, .

.

hey,
less rolling circumference means less rubber on the road .which in turn means less resistance the engine.so shouldnt the FE go up????


also less circumference means greater speedo error,which in turn will show slightly more kms on the odo and the speedo.
so here also u should get higher figures.



and i am not talking abt upsizes.i am talking abt a new tire of the same size.
?????????
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Old 12th April 2005, 15:09   #4
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Quote:
hey,
less rolling circumference means less rubber on the road .which in turn means less resistance the engine.so shouldnt the FE go up????
Smaller circumference means less distance per revolution. So, you're engine will actualy be revving a little higher at 100 on worn out tyres when compared to new ones. Higher rpm equates to higher fuel consumption and even when you calculate your kmpl, the new tyre will take lesser revolutions to complete the km than a worn out tyre.

And lastly. Rolling resistance is dependant on a lot of factors. A 19/60 R14 S322 could have a higher rolling resistance than a 195/60 R14 GIII or F1 Eagle. i'm not saying that is the case but it's very possible.

Shan2nu

Last edited by Shan2nu : 12th April 2005 at 15:30.
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Old 12th April 2005, 15:56   #5
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Quote:
Originally Posted by Shan2nu
Smaller circumference means less distance per revolution.

yeah so that means ,the odo reading will be more than that of a tire which is neweras it will have greater circumference.this difference will be negligible,but it will be difffernt.


or can we say that the engine will burn less fuel to reach higher revvs on a worn tire.
i am not talking abt a completely worn tire.


so a brand new tire may offer better grip ,but at the same time its gonna consume more fuel to reach the same revvs. than on a more worn tire.

so i cannot understabd as to how do people claim to get better FE on newer tires.

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Old 12th April 2005, 16:29   #6
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Quote:
so i cannot understabd as to how do people claim to get better FE on newer tires.
A grippy tyre need not necessarily have a higher rolling resistance. Tyre design plays a major role in it. Even my 195mm GIII roll much freely than the worn out S322s did.

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Old 12th April 2005, 19:38   #7
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wont the tires spin if they dont have grip hence loosing lots of power . so fuel taken from point A to point B should be more.one more point

There are lot of factors involved here. exactly dont know which plays more role. I think mileage increases with new tires and it fells good abt the car.
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Old 13th April 2005, 01:48   #8
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Quote:
Originally Posted by speedsatya
guys,

when tires get worn off,the traction offered by these worn tires decrease with every km.
as a result the grip offered will also be lesser.
so theoretically,the FE should increase .

and when u fit new tires of the same size,the grip offered is better .which should mean lesser FE due to improved traction.


but we see everyone saying that their FE has improved after fitiing new tires of the same size.


is this possible????????


satya
in my case, the FE has gone up hugely by 1.5 - 2 kms
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