can anyone teel me if increasing tire width decreases car performance
11-09-2002, 09:48 PM
#1
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can anyone teel me if increasing tire width decreases car performance
The more I research, the less I feel I know. I was simplistically thinking wider tires just meant better grip but now I am getting confused. Can anyone answer these questions for me:
1. If I increase my tire width to lets say 285 rear and 255 ft's, will the increase in tire width (wt increase and tire resistance to road) decrease my actual performance such as acceleration?
2. I noticed the ratio of understeer may be related to width of ft tire to rear and it appears people here are suggestioning to keep the same ratio on ft to rear when increasing tire size. Why do cars like a ferrari F40 have a hugh difference in ft to rear tires (235 fts vs 335 rears) without drastic over/understeer problems?
3. Most people on this forum seem to be going toward 19" rims and 30 series tires yet when i look at a porche 959, McLaren F1, and a Ferrari F40, they all have 17 inch rims and 45 series tires. Why do these untra expensive performance cars stay away from 19" rims and 30 series tires if they perform so weel? It cannot be the cost of the wheels and tires, it seems like cost is no issue for these cars?
Thanks guys for giving me feedback. I am sure someone knows more about this than myself!!!!
1. If I increase my tire width to lets say 285 rear and 255 ft's, will the increase in tire width (wt increase and tire resistance to road) decrease my actual performance such as acceleration?
2. I noticed the ratio of understeer may be related to width of ft tire to rear and it appears people here are suggestioning to keep the same ratio on ft to rear when increasing tire size. Why do cars like a ferrari F40 have a hugh difference in ft to rear tires (235 fts vs 335 rears) without drastic over/understeer problems?
3. Most people on this forum seem to be going toward 19" rims and 30 series tires yet when i look at a porche 959, McLaren F1, and a Ferrari F40, they all have 17 inch rims and 45 series tires. Why do these untra expensive performance cars stay away from 19" rims and 30 series tires if they perform so weel? It cannot be the cost of the wheels and tires, it seems like cost is no issue for these cars?
Thanks guys for giving me feedback. I am sure someone knows more about this than myself!!!!
11-09-2002, 10:35 PM
#2
you will increase resistance to the road, but to a certain degree you can offset this and then some, by launching at higher RPMs and taking turns faster. MPG on highway is likely to suffer somewhat tho.
as for understeer... I personally like to think of front and back seperatly. you have 8" fronts, if you go to a 9, you then have more traction, meaning you can go faster before you lose traction. you might be able to raise the speed on that to a higher number than the rears can handle before they lose traction. if you raise both tires, then you can take turns faster, but the handling characteristics remain the same, they are simply shifted to a higher speed. instead of getting understeer at 60, youll get it at 70... see what Im saying?
exotics are rear engine, they have weight over the rears pushing on it. they also have a CRAP load of torque and whatnot, so they can step on the gas and break the traction lose.
even with much wider tires.
lastly rims are heavy, and sidewall can be your freind for over all performance, more forgiving, absorbs some road imperfections. a 17" rim is hardly small, and the tires are not nescessarily that large.
hope this helps somewhat.
as for understeer... I personally like to think of front and back seperatly. you have 8" fronts, if you go to a 9, you then have more traction, meaning you can go faster before you lose traction. you might be able to raise the speed on that to a higher number than the rears can handle before they lose traction. if you raise both tires, then you can take turns faster, but the handling characteristics remain the same, they are simply shifted to a higher speed. instead of getting understeer at 60, youll get it at 70... see what Im saying?
exotics are rear engine, they have weight over the rears pushing on it. they also have a CRAP load of torque and whatnot, so they can step on the gas and break the traction lose.
even with much wider tires.
lastly rims are heavy, and sidewall can be your freind for over all performance, more forgiving, absorbs some road imperfections. a 17" rim is hardly small, and the tires are not nescessarily that large.
hope this helps somewhat.
11-10-2002, 09:07 AM
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let's talk physic :)
I don't have the experience of changing to a much wider tire but I would like to think about every mod in a more scientific way.
If you look at friction from the physic point of view, you'll notice that it only depends on the down force (the weight of your car) and the friction coefficient of the contacting materials. This implies the area (or the width of tires) is not a factor in measuring friction. I'll try to explain why a wider tire has the same friction than a less wider tire. If you take two different width tires with same material, and load them with the same weight. Then measure the friction in a very small area say 1cm^2. You'll notice the wider tire will have less friction because less weight is pushing down in that area. Keep in mind that the weight is distributed evenly on the entire area. Just like a table, the more legs you have the less force on each leg. However, if you add all these area up, you'll find the friction is the same on each tire. Thus, friction doesn't depend on the width. Theoically, you can replace bicycle tires with the tires on car and still have the same friction as long as they are built with the same material Funny ah?
However, they never do that on a F1 race car, why? Because heat has to be considered too. The friction coefficient decreases as temperature increases. The reason why people put wider tires on a F1 car is because, they spread the heat better. So, at high speed, the friction doesn't decrease as much.
I have this wrong idea before too... Everyone get this idea because usually wider tires are build of better material. So, if you are not thinking of racing on a high way or ract track, change to a better type of tire will give you better handling and won't cost you as much. So, look at the tire rating first before looking at the width.
I think I've talked too much. Good luck ;-)
If you look at friction from the physic point of view, you'll notice that it only depends on the down force (the weight of your car) and the friction coefficient of the contacting materials. This implies the area (or the width of tires) is not a factor in measuring friction. I'll try to explain why a wider tire has the same friction than a less wider tire. If you take two different width tires with same material, and load them with the same weight. Then measure the friction in a very small area say 1cm^2. You'll notice the wider tire will have less friction because less weight is pushing down in that area. Keep in mind that the weight is distributed evenly on the entire area. Just like a table, the more legs you have the less force on each leg. However, if you add all these area up, you'll find the friction is the same on each tire. Thus, friction doesn't depend on the width. Theoically, you can replace bicycle tires with the tires on car and still have the same friction as long as they are built with the same material Funny ah?
However, they never do that on a F1 race car, why? Because heat has to be considered too. The friction coefficient decreases as temperature increases. The reason why people put wider tires on a F1 car is because, they spread the heat better. So, at high speed, the friction doesn't decrease as much.
I have this wrong idea before too... Everyone get this idea because usually wider tires are build of better material. So, if you are not thinking of racing on a high way or ract track, change to a better type of tire will give you better handling and won't cost you as much. So, look at the tire rating first before looking at the width.
I think I've talked too much. Good luck ;-)
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