I've been doing a little at home testing over the last couple days. Figured I'd get some input from those guys who have more experience tracking their cars.

This started when I pulled my tires to rotate them to get ready for next weekends HPDE, and I realized I had excessive wear on my front tires as a result of my outing at Texas World Speedway (Clockwise).

Alignment going in:
6.9* caster both sides, 1.2* camber both sides, .15 toe in.
32 psi cold on all 4 corners

Tires:
Michelin Pilot Super Sport 265/40/18 on all 4 corners

Picture of rears next to fronts:
Right Rear on left, Right Front on right (facing same direction):

Left front on left, left rear on right (facing opposite directions):


Measurements of tires:
LF: inside slats, inside line, 2nd line, 3rd line, outside line, outside slat
LF: .100, .209, .211, .217, .151, .00
LR: .121, .237, .261, .260, .209,.058
RF: .118, .211, .220, .206, .154, .029
RR: .108, .235, .259, .253, .210, .062

Next, I went to do some skidpad work and measure tire temps.

Outer / middle / inner:
Pre- skidpad, after driving 20-30 minutes.
fronts: left 113,120,109
right 103,106,102

5 skidpad turns rt at Horse Track parking lot:
LF:137,138,107 (35 psi 2 min aft, 33 psi before left house)
LR:99,104,103 (33 psi hot, 31 before?)

This morning I added AndyF's camber spacers, which added around 1.2-1.3* of camber to my set-up.

Back out on the skidpad:
5 turns at outlet mall parking lot:
117/115/100 LF 33 psi as tested. Baseline.
110/108/100 LF 30 psi. Tire rolling more than I'd like.
120/117/101 LF 26 psi. Tire rolled past wear arrow.
125/123/105 LF 37 psi, FAST. 3400 rpm vs just over 2000 at 26 psi. Stable, solid feel. More balanced.

I also marked the tires with chalk, though even 37 psi rolled the tires slightly past the tip of the arrow.
37 psi with chalk:

Picture of arrow before chalk (this was the LR tire that is now in the LF position.)


At this point, I'm going to run the car with the additional camber (so ~2.5* total camber now), and up the tire pressures to that Hotchkis used in the Hot Rod tire test article (38/34 cold). I'm also going to flip the rears (which were the fronts), so the heavy wear now sits inside. If the fronts wear the outside edges too fast on saturday, I might flip those as well.

I'm also considering really torquing down the front sway bar end links, to reduce the rubber deflection and reduce body roll.


I'll also measure tire temps and wear at the track on saturday and sunday.

Any experienced racers have thoughts on what caused my abnormal tire wear? A combination of too low pressure and not enough negative camber? Or?

And the skidpad test - the numbers make sense, but I thought the test was telling me to drop tire pressure, given the temps were not linear. Obviously not the case. Further, I expected my adjustments both to camber and psi to have more of an impact on tire temperatures (granted the increased camber did cut down the gap). I'm not sure more camber is the answer with 'street' tires. Thoughts?

Thanks!
Wade