[dave968]

I am getting ready to put my 2nd set of Kumho V710s on my 968 and noticed that the tire wear looks like I am not using the shoulder of the tire. When I read about the care and feeding of the Kumhos vs the Hoosiers R6 that I ran before, I was suprised that Kumho recommended camber in the -.5 to -1.5 range while Hoosier recommended camber -3. Also Kumho recommended lower inflation pressures, and specifically said to target hot inflation pressures of 28-32 psi. I have been previously told to think cold inflation pressures when setting tire pressures. Hoosier recommends hot pressures of 38-43 and cold pressures of 27-33. My 968 is set up for the track only with M030 sway bars, Leda shocks, front springs 800 lb and rears 700 lbs. My current alignment is -2 front camber and -2.7 rear camber. I am running front tires 245-35-18 and rears 280-30-18.

I think I was running too much cold inflation pressure at 34 lbs and not checking hot inflation pressures-- Could this have caused my tire wear not using the shoulder area of the tread?

I was planning on changing my alignment to -3.4 neg camber front and -2.4 rear, but now wonder if as Kumho recommends I should use less negative camber even only -1.5???

Thanks

Dave

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[968crazy]

from what I've seen hoosiers use up the outside shoulder of the tire reaaly quick if you dont have enough camber and they also need more tire pressure than other tires. I run -2.5 front and -1.5 rear and I've used kumhos and the new bfg R1s with no problems. I think -3.4 is a bit too much unlessyou are going to run hoosiers.

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[Eric_K]

It looks like most of the wear is in the center of the tire. I think you were running way too high of a pressure. Cold pressure is meaningless. It is just a reference to get you near your desired hot pressure at the start of the day. Always measure the hot tire pressure and do it as soon as you come off the track. You want to know the pressure when it is as close to operating temperature as possible. If you were starting at 34 you were probably in the mid-40's hot. 34 would be a good hot pressure. IMO, -3 front, -2 rear camber would be a good starting point and adjust from there based on how the tire responds when it is at a proper pressure.

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[vnarma]

I have always found the V710 need much lower pressures to start than the Hoosiers. I would start in the 26/28 range here in the NorthEast. I see very progressive wear, and excellent Grip. In warmer/colder climate this may vary. This worked out to 32/34 hot. Above that, you get uneven wear, and they get greasy, which is not normally the case. I'm running 2.5 degrees front, 1.6 in the rear. Car is 49/51 f/3 balanced.

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[flash]

while not the same thing exactly, but follow with me and this might make sense



i have recently found that i need to DECREASE my negative camber - this is because i have significantly reduced the amount of body roll with my new swaybars



adding negative camber is supposed to try to find a balance between left and right tire contact patch areas and increase the net contact patch area during a turn - if the car isn't rolling as much, less camber is needed - having too much can actually reduce the amount of net contact patch area



stiff sidewalls can easily contribute to this too



this is what i think you probably have going on - the kumhos are probably stiffer than the hoosiers - they would therefore need less air and camber to achieve the same net contact patch area - they might be a bit tougher to get to grip on cold days though, and have a bit more of a tendency to scitter on the rumble strips

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