Overall tire height increase VS tire/wheel width + unsprung weight increase?
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Joined: Feb 2021
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From: Metro Detroit
E550
Overall tire height increase VS tire/wheel width + unsprung weight increase?
Let’s have a technical conversation. Theory is alright here, as there are too many factors that influence the calculations.
If you’re reading this, you may know that straight line traction can be improved with both an increase in overall tire height, and/or an increase in tire contact surface area (tire width, with a corresponding wheel width increase).
Lets assume traction is perfect in both cars (4matic), and that they accelerate equally otherwise, utilizing the exact same tire and wheel type. We are also setting “looks” and ride comfort aside.
Car A has a square wheel and tire setup, 20x9 with a 265/30/20.
Car B has a staggered setup, 20x9 with a 245/30/20 and 20x10 with a 295/25/20.
Car A’s setup is 0.5” taller than Car B’s. As we know, a taller tire requires more rotational force to turn it. However, Car B’s setup is roughly 5lbs heavier (-4lbs in front, +9lbs in rear). As we know, more unsprung weight requires more rotational force to turn it.
Yes, these numbers are insignificant. Yes, the 265 setup will be less harsh on bumps. However, I do believe a taller tire, at this ratio to unsprung weight, is going to be the slower car in a straight line. I “think” that taller tire multiplies the torque required to overcome the existing weight of the rotating parts.
I know on some Corvette Z06/ZR1 groups, people advise to not go up in tire height if they can avoid it. This does however leave some MPH on the table on the big end of a run. So it’s a balancing act of down low power and trap speed with your gearing.
Do you follow my theory? I think since traction really isn’t an issue for our AWD cars under 600hp, focusing on efficiency in power application becomes an effective strategy for reducing driveline stress and reducing 0-60ft, 0-60mph, and 1/8th mile times. Thoughts?
If you’re reading this, you may know that straight line traction can be improved with both an increase in overall tire height, and/or an increase in tire contact surface area (tire width, with a corresponding wheel width increase).
Lets assume traction is perfect in both cars (4matic), and that they accelerate equally otherwise, utilizing the exact same tire and wheel type. We are also setting “looks” and ride comfort aside.
Car A has a square wheel and tire setup, 20x9 with a 265/30/20.
Car B has a staggered setup, 20x9 with a 245/30/20 and 20x10 with a 295/25/20.
Car A’s setup is 0.5” taller than Car B’s. As we know, a taller tire requires more rotational force to turn it. However, Car B’s setup is roughly 5lbs heavier (-4lbs in front, +9lbs in rear). As we know, more unsprung weight requires more rotational force to turn it.
Yes, these numbers are insignificant. Yes, the 265 setup will be less harsh on bumps. However, I do believe a taller tire, at this ratio to unsprung weight, is going to be the slower car in a straight line. I “think” that taller tire multiplies the torque required to overcome the existing weight of the rotating parts.
I know on some Corvette Z06/ZR1 groups, people advise to not go up in tire height if they can avoid it. This does however leave some MPH on the table on the big end of a run. So it’s a balancing act of down low power and trap speed with your gearing.
Do you follow my theory? I think since traction really isn’t an issue for our AWD cars under 600hp, focusing on efficiency in power application becomes an effective strategy for reducing driveline stress and reducing 0-60ft, 0-60mph, and 1/8th mile times. Thoughts?
