I'm hoping you can shed some light on air pressure and how it effects the hadnling characteristics of a car - particularly at an autocross. I'm a bit confused by it all...

What does increasing or decreasing pressure do to the characteristics of the car?
What about front to rear pressure differences?

Any insight on this topic would be great. I'm still (and always) learning...

 

Take a look at the June Grassroots Mag in the tire tech article on Page 156, it gives good info on this subject. Also, I post some info on this in this post.
https://honda-tech.com/zerothread?id=164340

EC

 

Basically: when you're cornering, your tires are flexing sideways. Therefore, they will always take a line slighty longer than the radius you're actually turning. I call this drift. The more the momentum of the car is opposing the direction the tire is pointing, the more the tire will drift. Technically, the difference between the tire's pointing direction and traveling direction is called "slip angle."
Now, the more air you have in your tires, the less they'll flex, and the less slip they'll allow. Also, a Prelude is a very frontheavy car, so the front tires are describing a larger turning radius than the rear, due to the greater force on them, and thus the greater slip angle (not to mention, they're turned!). This makes it very hard to get the car around a real tight corner at speed. So people like to run high pressure in the front (max psi or a little over), and low pressure in the back (min recommended psi). That way, the back end of the car will drift farther and the front will drift less, improving turn-in. Or at least, they'll be more even than before.
Of course, adjust your pressures within reason!
Hope this helps.
-Dan

 

Anyone else? I would also like to know....

 

There seems to be two schools of thought on autox pressures...one is to put the rears up really high, the other is to drop them down really low. Both methods are intended to help rotate the rear of the car. Personally, I don't like the idea of running really low pressures and beating the crap out of the sidewalls. When I autox'd on stock RE010s, I started out at 40/40 and once I was comfortable and needed more rotation on tight turns I ran 40/42. This f/r tire pressure combo seems to work great with the lift throttle oversteer technique.

 

Now I am really confused, how can increasing the rear pressure and decreasing the rear pressure both do the same thing? Which is it?

 

every tire has its own optimal tire pressure that will provide the most grip while not rolling over, any time you go outside the optimal pressure, either higher or lower you are losing effective traction.

 

See the above post. Both methods will work...I prefer higher pressures in the rear. You can take your pick.