Track Tire Pressure Difference

While on a basic level I understand the reason to carry lower tire pressure during track/race events. What are the pros and cons of doing so? Also, what occurs besides quicker treadwear if lower pressures are used on the street? Any "rules of thumb" for such practices? Kento maybe the Geek could do a story on the science/art(if he hasn't already) of tire pressures in the magazine.

I'm also curious why in a track situation you'd have more front tire pressure than rear tire pressure when tire manufacturers recommend more rear tire pressure than front tire pressure: usually around 32-34 PSI front and 42 PSI rear for street applications.  

The reason you see (starting) lower rear tire pressures on our track tests is because DOT race tires (especially the rear) have a different construction that allows them to run such low pressures. Standard sport street tires must have more compromises towards high speed stability and tread wear in their internal and tread construction, thus requiring higher pressure. Running standard sport tires at such low pressures would be detrimental to handling as well as tread wear, since they're not built with those low pressures in mind.

All that said, the manufacturer recommendations for OEM street tires are always on the high side, because they want to cover all possible bases in street riding scenarios (i.e., passenger, luggage, heavy rider). Generally with sport street tires, you can start with 34 psi in the front, and 36 psi in the rear, and adjust from there to get the grip and handling you want. Lower pressures allow better bump absorption and better grip (at the expense of tire life) to a point. You don't want to go any lower 30 front/32 rear with sport street tires.

Also moving this over to the Tech section.  

Thank you for the response that clears up the track item. As I usually ride mainly on the street with an occassional track day I don't buy DOT race tires as the street/track day type tires do a good job. I'm sure the DOT race tires would provide a bit more grip compared to street tires but as these tires would wear quicker and likely require more frequent changes they'd add to an already constrained budget.

Also, thanks for the recommendations on street tires. I tend to run btwn 32-34 front and 38 or so for the rear on my street tires but agree lower pressures on street tires is at the expense of tire life.