Originally Posted by ckhaber
Not knowing to much about tires, i purchased med.The weather here is hot,32C when i run.Road surface must be 30% higher.Chris
Not wanting to start a "ruckus" on tires here, so please, lets strictly deal with science & physics.
Since the majority of the conversations being discussed here are top-speed related topics, letís focus there and the laws of physics that determine the science behind any rubberís effectiveness at speed.
Things to consider are different shore rubber, their ability to manage the culmination of heat generated by motor torque, road surface temperature, asphalt texture and high speed wind resistance induced tire slip. These variables hold true, regardless of manufacture or brand.
The harder the rubber shore, the greater heat management properties it will have and the longer it can maintain it. This doesnít mean that the hardest rubber shores are always most desirable, but rubber shores that are too soft for their intended application or the operating conditions they will experience is not always best either.
The type or firmness of a tireís foam insert also attributes to any rubber shoreís heat management abilities, the duration of time they can maintain effective traction and the amount of tire life they will provide.
Soft foam insert allows rubber to reach higher temperatures faster than a harder foam insert. Softer foam inserts are sometimes desirable in drag or road racing track racing applications during short runs or qualifying scenarios of the shorter duration and lower operating speeds; where mechanical grip seems the primary concern.
Unfortunately soft foam inserts are more prone to excessive hear build up, loss of extended traction (due to overheating), greater rolling resistance and rapid tire wear. Harder foam inserts provide more gradual heat generation, less rolling resistance and longer tire life.
When rubber is overheated it becomes greasy, loses traction and eventually begins to melt; once again itís physics on action. In order to optimize traction, durability and tire life, one must consider the many different variables a carís tires will be experiencing and itís also good to equate foam inserts with simulated tire air pressure.
Try thinking of foam insets as follows: soft insert=low air pressure and hard inserts=high air pressure. So, in regards to top speed running, more simulated tire air pressure will result in lower friction and reduced rolling resistance for greater top speed efficiency.
The laws of physics regarding rubber properties are evident in full size car and should be considered too.
Just look at the differences between drag racing, road racing and top speed racing, none use the same types of tires for good reason. Drag slicks are super soft, hook up great, but wear out very fast.
Road race or Nascar tires are harder because they must endure more time usage between tire changes.
Top speed tires are typically harder because of their ability to maintain effectiveness, reduced rolling resistance and safety over the long haul.
Sorry for the long post, but thereís a lot of science to consider when talking about tires. I hope this post helps some of you to better understand some of it all. Take care!