# Calculating Tractive Force

1. Sep 29, 2009

### skt

Is the formula for tractive force = wheel torque/tyre radius, or wheel torque x tyre radius?

2. Sep 29, 2009

### xxChrisxx

T = F x D

3. Sep 30, 2009

### skt

Basically, do you simply take the diameter of the crown wheel and tyre, then proceed to calculate the ratio between the two; therefore giving a reduction in torque?

4. Sep 30, 2009

### xxChrisxx

Torque = Force x Distance.
(What I wrote above was kind of ambiguous, sorry)

Rearranging for force gives torque / distance.

So in this case it's wheel torque / the rolling radius (from cenre of wheel to outer egde of tyre).

The wheel torque is the torque from the engine * the drive ratios of geabox * final dive ratio.

5. Sep 30, 2009

### Ranger Mike

see post below in gen pyshics forumn..
Wider tire giving better traction debate! Old Aug15-09, 04:19 AM

also..you must measure radius of the tire..with mounted on the car, with full fuel, driver...
because it will change from free state

thing 2?? are you going straight or plan on turning at speed..see several posts on centifugal force, tire contact, tire friction etc..