Beta Tyre Wear and Thermals Redux 0.20

Completely reworked wear

• Wear is now also based on how much vertical force is on the tyre relative to the vehicle's total mass, (it should've been already but I've only recently found a way to do it)
  
• Previously, wear seemed to be primarily based on distance travelled, rather than how hard the car is being driven, this is no longer the case and is now related to temperature, slip and vertical load (among other things like the tyre width, though that hasn't changed in this update)