How to calculate force needed to get a tire spinning

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    Force Spinning Tire
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Discussion Overview

The discussion revolves around calculating the force required to start a tire spinning or rolling, particularly in the context of comparing different tire sizes and weights for vehicles like side by sides or UTVs. Participants explore various factors that may influence this force, including tire specifications, weight, and surface interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about the specific conditions under which the force is to be calculated, such as whether the tire is on the ground or spinning in air, and whether the vehicle is in gear.
  • There is mention of key factors affecting the calculation, including the coefficient of friction, weight on the wheel, and wheel diameter.
  • One participant suggests that the coefficient of friction could be assumed to be 1 or 0.50, affecting the force needed to start the tire spinning or rolling.
  • Another participant emphasizes the need to clarify whether the focus is on rolling resistance or spinning (slipping) resistance, as they are fundamentally different.
  • Concerns are raised about the clarity of the original question, with some participants requesting more detailed information to provide meaningful assistance.
  • There is a suggestion that the tire's rubber compound and footprint on the road may also influence the calculations.
  • One participant expresses a desire for objective facts to aid in tire selection, acknowledging the difficulty in obtaining specific information.
  • A later reply questions the necessity of the detailed factors discussed if the ultimate goal is simply to choose the right tire.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific calculations needed or the relevance of various factors. Multiple competing views remain regarding the importance of different parameters and the clarity of the original question.

Contextual Notes

Participants highlight the need for more information about the scenario being analyzed, including the conditions under which the force is applied and the specific goals of the calculation. There is also uncertainty about the definitions of terms like "starting torque" and whether the focus is on rolling or slipping resistance.

sugarray
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I am looking for an application to see how much force is needed to start a tire spinning to compare different sizes and weights of different brands of tires.

This is to help give an idea of stress on a transmission.

I have searched an hour hear as well as Google looking for a formula or calculator, but have been unsuccessful.
 
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sugarray said:
I am looking for an application to see how much force is needed to start a tire spinning to compare different sizes and weights of different brands of tires.

This is to help give an idea of stress on a transmission.

I have searched an hour hear as well as Google looking for a formula or calculator, but have been unsuccessful.
Your question is not at all clear. Force from what? Why would this stress the transmission? Get the tire spinning under what conditions? Why would tire brand or size matter?

Please describe exactly the scenario you are trying to analyze.
 
I am interested in the force required to start a tire moving from a dead stop on my side by side/UTV.

Using the weight of the tire and the diameter of the tire and maybe the rolling resistance, if published.

I want to compare how weight and size of tire affect the force needed to start a tire rolling. This will allow me to compare say, BF Goodrich/Tusk/Tensor/Sedona tires of 28" and 30" diameters in a standard way to help aid my decision in which tire to purchase.
 
The key factors in making this calculation are coefficient of friction, weight on the wheel and wheel diameter.

Here are some hints:

1. If you assume a coefficient of friction between the tire and the surface of the road to be 1 then it will take as much force to slid (spin) the wheel as is pushing down on that wheel.
If you assume a coefficient of 0.50 then it would take only 1/2 the weight on that wheel to slid the tire. BTW-This force is perpendicular to the applied weight and right at the road surface.

2. How do you get this force to be applied right at the interface of the wheel and the road surface?

3. How does the diameter of the wheel fit into the equation?

4. How does the tires’ rubber compound effect the equation?
5. How does the footprint made by the tire on the road effect the equation?
What do you think?
BTW - Do you mean rolling or sliding (spinning)?
 
Last edited:
AZFIREBALL said:
The key factors in making this calculation are coefficient of friction, weight on the wheel and wheel diameter.

Here are some hints:

1. If you assume a coefficient of friction between the tire and the surface of the road to be 1 then it will take as much force to slid (spin) the wheel as is pushing down on that wheel.
If you assume a coefficient of 0.50 then it would take only 1/2 the weight on that wheel to slid the tire. BTW-This force is perpendicular to the applied weight and right at the road surface.

2. How do you get this force to be applied right at the interface of the wheel and the road surface?

3. How does the diameter of the wheel fit into the equation?

4. How does the tires’ rubber compound effect the equation?
5. How does the footprint made by the tire on the road effect the equation?
What do you think?

I think I’m not wanting that much specificity. Which was a concern when I posted. It might not be possible to get the information I’m wanting, and that’s ok. I’m just looking for some how to add a little science into my decision process. Everyone has an opinion on which tire is best, but objective facts would be nice.
My physics classes were A LONG time ago. So, I came here for a little help. If that help ends up being that I can’t get the info I’m looking for, then that’s fine. Reading through the posts during my search, you are some smart folks here, so anything helps.
 
We expect you to invest a little into the process of finding the answer. Just like in school!
 
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sugarray said:
I am interested in the force required to start a tire moving from a dead stop on my side by side/UTV.
Is this tire on the ground or spinning in air? You said "spinning" in your first post. Is the vehicle in gear? What force is making it "spin" - the engine torque? Are you just trying to get the tire to turn or are you really trying to find out what it takes to get the vehicle to move?
Using the weight of the tire and the diameter of the tire and maybe the rolling resistance, if published.

I want to compare how weight and size of tire affect the force needed to start a tire rolling. This will allow me to compare say, BF Goodrich/Tusk/Tensor/Sedona tires of 28" and 30" diameters in a standard way to help aid my decision in which tire to purchase.
Why do you think any of that matters?

Again, you need to put a lot more effort into this, not just so you can learn like in school, but also because with the information you've given us, we literally cannot help you. We have no idea what you are trying to do if you won't tell us. But if making a purchasing decision on the right tire for your vehicle is what you are ultimately after, then the short answer is that none of what you are saying matters.
 
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We should first determine if we are looking to solve for rolling resistance or spinning (slipping) resistance, as they are two very different things!
 
AZFIREBALL said:
The key factors in making this calculation are coefficient of friction, weight on the wheel and wheel diameter.

Here are some hints:

1. If you assume a coefficient of friction between the tire and the surface of the road to be 1 then it will take as much force to slid (spin) the wheel as is pushing down on that wheel.
If you assume a coefficient of 0.50 then it would take only 1/2 the weight on that wheel to slid the tire. BTW-This force is perpendicular to the applied weight and right at the road surface.

2. How do you get this force to be applied right at the interface of the wheel and the road surface?

3. How does the diameter of the wheel fit into the equation?

4. How does the tires’ rubber compound effect the equation?
5. How does the footprint made by the tire on the road effect the equation?
What do you think?
BTW - Do you mean rolling or sliding (spinning)?
hey azfireball,
how to proceed if i want to calculate the starting torque required for a bike weighing 120 kg and a load of 150kg with tyre specification of 120/70 r12.
 
  • #10
First define 'starting torque'. Do you mean to just start it rolling, or to start it spinning (slipping) while on a surface with a 270 kg load applied? Where is the torque applied...at the wheel or on the pedals?
 
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  • #11
OP has not returned to expand and the recent discussion has prompted a new thread, so I'm closing this.
 

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