What is positive traction?

JP wrote:

> I need some help from anyone who is familiar with older VW beetles. This
> could help me in a criminal case. I am looking for documentation that would
> give me the wheel base and track measurements and if any VW beetles has
> positive traction. I have tire tracks in my yard that are associated with a
> violent attack on a family member. I have reason to believe it was my
> neighbor who drives an older model VW beetle convertable. Please email me if
> you can help. THANKS in advance!
>
> (remove NOSPAM to email me.)