The first tale of the dragon...(long)
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Joined: Oct 2000
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From: Knoxville
OMG!!! We had a great time today! We had a last count 67 cars at Westside Honda in Knoxville today. I would imagine there will be ~100 in Asheville over the weekend. It was so good to put faces with the names. I don't have my digital camera cord with me or I would post the pics I took. The first thing I noticed was the shredded front tires on several cars with incorrect air pressure. The second was how everyone was keeping up with the cycles. Everyone behaved and it was a good time had by all, except for one who ran off the road and had to turn around and have an alignment done! Two runs was enough for us so we headed back home. Everyone be safe on the trip to Asheville, I wish I was continuing on 
I am grateful to everyone for making my day!
Thanks for coming to see us in Knoxville!
Larry and Mitzi
I am grateful to everyone for making my day!
Thanks for coming to see us in Knoxville!
Larry and Mitzi
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Joined: Oct 2000
Posts: 390
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From: Knoxville
No, this guy was from Texas I think. And about the tires... it was definately a pressure issue. One of the cars was running at 31 HOT!
I was sqealing through many turns and did not have the same result - you should have seen them - they were actually peeling in places!
I was sqealing through many turns and did not have the same result - you should have seen them - they were actually peeling in places!
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From: Melbourne!
Krazik, we've been down this route before in many other threads. In Australia before you are allowed out on the track for a high performance driving day the school owners will insist that you pump the tyres up to manufacturers recommended presure (32psi) + at least an additional 10% (3.2psi) = 35psi COLD. They do this in order that they don't have their students sliding off the track and wrecking their vehicles.
I personally run around 38-39 cold on both road and track and find that this offers the best grip/wear combination. The tyres are rated to max 44psi so there is plenty of room for more air.
I personally run around 38-39 cold on both road and track and find that this offers the best grip/wear combination. The tyres are rated to max 44psi so there is plenty of room for more air.
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From: You wish
The tire pressure issue should probably go to racing or under the hood, but...
I also find that the starting pressure I need to run at the track is below my normal street pressure. Why? The reason is simple, for optimum grip on the average surface, there is an optimum hot pressure (this is a generalization, but sufficient for the purposes of discussion). When driving on the street, I generate a certain amount of heat in the tires. This increases pressure a particular amount. If I set my cold pressure properly I'll hit my optimum hot pressure and get good grip when I need it. On the track, I am working the tires much harder. This means the tires are creating more heat, raising the air pressure further. This may put my actual pressure beyond optimum.
I find that anything more than 33 fr/35 rr is too much for me on the street. More front pressure (at least up to 35 psi) increased oversteer (more front grip) and more rear pressure also reduces back end grip for my driving style. This pressure also works well for me in auto-x (on OEM tires) with no rollover or scrubbing probs, but auto-x's are short. I did drop the pressure slightly at the one track event I've done in the car.
In short, more pressure on street radials usually means more grip because of a more stable sidewall, to a point. On most cars, anything more than 4-5 psi above recommended begins to make me worry about contact patch issues. Radial contact patches are pretty stable within a certain range, but even they can have a size reduction by using too high a pressure.
UL
I also find that the starting pressure I need to run at the track is below my normal street pressure. Why? The reason is simple, for optimum grip on the average surface, there is an optimum hot pressure (this is a generalization, but sufficient for the purposes of discussion). When driving on the street, I generate a certain amount of heat in the tires. This increases pressure a particular amount. If I set my cold pressure properly I'll hit my optimum hot pressure and get good grip when I need it. On the track, I am working the tires much harder. This means the tires are creating more heat, raising the air pressure further. This may put my actual pressure beyond optimum.
I find that anything more than 33 fr/35 rr is too much for me on the street. More front pressure (at least up to 35 psi) increased oversteer (more front grip) and more rear pressure also reduces back end grip for my driving style. This pressure also works well for me in auto-x (on OEM tires) with no rollover or scrubbing probs, but auto-x's are short. I did drop the pressure slightly at the one track event I've done in the car.
In short, more pressure on street radials usually means more grip because of a more stable sidewall, to a point. On most cars, anything more than 4-5 psi above recommended begins to make me worry about contact patch issues. Radial contact patches are pretty stable within a certain range, but even they can have a size reduction by using too high a pressure.
UL