Stretching tires
07-29-2009, 09:18 AM
#42
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I was looking at different tire sizes for the front, and toyo makes a 205 35 18 now. A guy put one on a 8.5" wheel. Here is a pic. Crazy looking streach.
07-29-2009, 10:50 AM
#43
This is one of the most misleading threads I have came across in a while. Anybody looking for technical information beware.
Some info from a book I read written by a world class tire engineer, not a sales rep/retailer. Anybody more interested, I suggest you buy it and read it. Paul Haney "The Racing and Performance Tire"
First of all, stretching rubber (radial tires) effectively decreases the tire spring rate (z-component). The sidewall tension in the lateral direction (x-component) is increased.
The information you are about to read pertains to Radial Tires.
Lateral force (grip) is generated when either of the side walls are under tension. The contact patch lags steering inputs. When a wheel/tire package allows the tire carcass to move laterally relative to the wheel centerline, there is a lag. When you stretch rubber, the side walls are effectively already in tension which creates faster transfer from steering input to contact patch movement.
Now, the main difference in characteristics between Bias Ply and Radial tires are that per given contact patch surface area and compound, the radial tires will create more lateral force. This is due to the different construction methods, mainly much stiffer side walls. The downside is that the breakaway characteristics are much less progressive. What this means is that the point @ which the lateral force vs. slip angle graph peaks, the slope of the line after the peak is reached is much steeper. This is why bias plys are so much fun to drive on, its much much easier to control slides, effectively large slip angles.
Like anything suspension related, tire tuning is a balance, and has many trade offs. Take it to an extreme and you will massively compromise behavior characteristics. Effectively stretching tires dramatizes the characteristics of radial tires.
Hope this helps.
-Dino
Some info from a book I read written by a world class tire engineer, not a sales rep/retailer. Anybody more interested, I suggest you buy it and read it. Paul Haney "The Racing and Performance Tire"
First of all, stretching rubber (radial tires) effectively decreases the tire spring rate (z-component). The sidewall tension in the lateral direction (x-component) is increased.
The information you are about to read pertains to Radial Tires.
Lateral force (grip) is generated when either of the side walls are under tension. The contact patch lags steering inputs. When a wheel/tire package allows the tire carcass to move laterally relative to the wheel centerline, there is a lag. When you stretch rubber, the side walls are effectively already in tension which creates faster transfer from steering input to contact patch movement.
Now, the main difference in characteristics between Bias Ply and Radial tires are that per given contact patch surface area and compound, the radial tires will create more lateral force. This is due to the different construction methods, mainly much stiffer side walls. The downside is that the breakaway characteristics are much less progressive. What this means is that the point @ which the lateral force vs. slip angle graph peaks, the slope of the line after the peak is reached is much steeper. This is why bias plys are so much fun to drive on, its much much easier to control slides, effectively large slip angles.
Like anything suspension related, tire tuning is a balance, and has many trade offs. Take it to an extreme and you will massively compromise behavior characteristics. Effectively stretching tires dramatizes the characteristics of radial tires.
Hope this helps.
-Dino
07-30-2009, 04:22 AM
#45
Originally Posted by Antonov,Jul 29 2009, 12:50 PM
This is one of the most misleading threads I have came across in a while. Anybody looking for technical information beware.
Some info from a book I read written by a world class tire engineer, not a sales rep/retailer. Anybody more interested, I suggest you buy it and read it. Paul Haney "The Racing and Performance Tire"
First of all, stretching rubber (radial tires) effectively decreases the tire spring rate (z-component). The sidewall tension in the lateral direction (x-component) is increased.
The information you are about to read pertains to Radial Tires.
Lateral force (grip) is generated when either of the side walls are under tension. The contact patch lags steering inputs. When a wheel/tire package allows the tire carcass to move laterally relative to the wheel centerline, there is a lag. When you stretch rubber, the side walls are effectively already in tension which creates faster transfer from steering input to contact patch movement.
Now, the main difference in characteristics between Bias Ply and Radial tires are that per given contact patch surface area and compound, the radial tires will create more lateral force. This is due to the different construction methods, mainly much stiffer side walls. The downside is that the breakaway characteristics are much less progressive. What this means is that the point @ which the lateral force vs. slip angle graph peaks, the slope of the line after the peak is reached is much steeper. This is why bias plys are so much fun to drive on, its much much easier to control slides, effectively large slip angles.
Like anything suspension related, tire tuning is a balance, and has many trade offs. Take it to an extreme and you will massively compromise behavior characteristics. Effectively stretching tires dramatizes the characteristics of radial tires.
Hope this helps.
-Dino
Some info from a book I read written by a world class tire engineer, not a sales rep/retailer. Anybody more interested, I suggest you buy it and read it. Paul Haney "The Racing and Performance Tire"
First of all, stretching rubber (radial tires) effectively decreases the tire spring rate (z-component). The sidewall tension in the lateral direction (x-component) is increased.
The information you are about to read pertains to Radial Tires.
Lateral force (grip) is generated when either of the side walls are under tension. The contact patch lags steering inputs. When a wheel/tire package allows the tire carcass to move laterally relative to the wheel centerline, there is a lag. When you stretch rubber, the side walls are effectively already in tension which creates faster transfer from steering input to contact patch movement.
Now, the main difference in characteristics between Bias Ply and Radial tires are that per given contact patch surface area and compound, the radial tires will create more lateral force. This is due to the different construction methods, mainly much stiffer side walls. The downside is that the breakaway characteristics are much less progressive. What this means is that the point @ which the lateral force vs. slip angle graph peaks, the slope of the line after the peak is reached is much steeper. This is why bias plys are so much fun to drive on, its much much easier to control slides, effectively large slip angles.
Like anything suspension related, tire tuning is a balance, and has many trade offs. Take it to an extreme and you will massively compromise behavior characteristics. Effectively stretching tires dramatizes the characteristics of radial tires.
Hope this helps.
-Dino
Sounds like it would be undesirable for racing but potentially desirable for drift, as it could help you get sideways more easily.
07-30-2009, 06:51 AM
#46
Banned
i think you may have read that wrong..
the way i understood that is .. stretching reduces input lag, but become less progressive at breakaway loads.
i think this is why you see alot of drift cars stretch the crap out of the front tires, more precise turning ability.
the way i understood that is .. stretching reduces input lag, but become less progressive at breakaway loads.
i think this is why you see alot of drift cars stretch the crap out of the front tires, more precise turning ability.
07-30-2009, 08:31 AM
#47
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Originally Posted by 2ooo,Jul 29 2009, 05:06 PM
This tire is on an 8.5" rim??
That's nuts. The spec for a 205/35/18 T1R is 7.0" to 8.0", and while 8.5" is outside the parameters, a 1/4" per side stretch will not typically produce results that look like that.....
That's nuts. The spec for a 205/35/18 T1R is 7.0" to 8.0", and while 8.5" is outside the parameters, a 1/4" per side stretch will not typically produce results that look like that.....
07-30-2009, 08:35 AM
#48
Registered User
[QUOTE=Tripleblackap1,Jul 30 2009, 10:31 AM] So, if the tire manufacture recommends a 7-8 for a 205, and Honda puts a 205 on a 6.5 on the ap1. The tire is stretched more than
07-30-2009, 05:47 PM
#50
Registered User
Tire stretching, especially on an S2000, contradicts everything a sports car is supposed to be about; agility in handling and braking. Aesthetics is an individual matter and I personally don't find the risk acceptable to mount tires outside the carefully engineered specifications for the sake of looks.