I had the opportunity to finally really play with tire pressures at yesterday's test and tune day. I started with the default 36f/32r and made 3 runs to get my time down for comparison. Kumho 225/245

I then pumped 'em up to 50f/44r as Roger Johnson had suggested some time ago (said that experimentation at an Evolution school showed the higher pressures to be superior). Ran 3 more times. I couldn't tell much difference - thought the rear was slightly looser than before but really didn't have any problems. My times were within a quarter second to dead even - basically lost in the noise.

To complete the experiment, I then went BACK to 36/32 and ran once (with a passenger). Had my best time of the day by .1 second.

Ron, you were trying 30 in the front - any results? I don't have a sway bar so it probably wouldn't make sense to try it myself. Who recommended this and why?

 

I am a novice, but what is the reason behind running lower pressure in the fronts than the rears?

I have only run one time on a track. Started with 38psi all around. After 30 minutes, rears measured 44.5psi due to heating.

 

[QUOTE]Originally posted by Tim S2K
[B]I am a novice, but what is the reason behind running lower pressure in the fronts than the rears?

I have only run one time on a track.

 

I am actually interested in the physics or reasoning behind different pressures in the front, vice the rears. I don't know.

I only ran 38psi all around because I am a novice.

 

Tim, my reasoning for running differential pressures is to adjust grip and responsiveness. This is in the same line of reasoning why Honda didn't pick the same size tires/wheels for all four corners of our S2K's. Depending on how you drive the stock stook you'll find both oversteer and understeer. I admit to fearing oversteer a bit more since looping makes me lose more time than a death-plow.

 

Thanks,

By "death-plow" do you mean a slide that takes out a line of cones?

 

The real question is what were your tire pressures hot? The tires on the car will reach different pressures depending on the track. The key is to get the pressures even side to side front and rear hot and to get the balance you want front to rear hot.

 

Tim, the death plow is referring to understeer - which can take out cones as easily as oversteer (a spin in the worst case).

 

[QUOTE]Originally posted by SteveS2K
[B]The real question is what were your tire pressures hot?

 

Before you make your runs, does one warm up the tires like they do with the motorcycles? One gets more traction from a warmed up tire. And, as someone suggested, are these tire pressures with a warmed up tire or cold? When Honda suggests pressures most likely it's after being driven and warmed up. Say, on the road while you're filling up at a station.