Hoosier rep feedback

[texevora]

Spoke at length with the Hoosier product manager that was at the SVRA championships in Austin (Circuit of the Americas).

Pestered him with numerous questions, figured I would pass along some interesting responses from him:

Heat cycling worth it or not? - his response was that for cars as light as ours, we would see little to no upside from heat cycling. Saves us a couple bucks if you are paying to have them pre-heat cycled, or time if you are doing it yourself on track.

Is the SM7 any different than the R7 compound? I had heard conflicting stories from non-Hoosier people. The Hoosier rep confirmed that they are identical compounds, just slightly different tread pattern.

Tire pressures? I told him i ran 14f/r cold and 17f/r hot and his eyes almost popped out of his head. He said that was way way way too low even considering the Atom's lightness, and recommended 22ish cold and 30ish hot. This conflicts with what I've seen other people post as their optimal, so i'll likely be experimenting with something in between (18ish cold, which I believe TMI reported as optimal). He said my pressures being that low were causing my rapid shoulder wear and likely leading to a smaller portion of the treat width making contact in turns.

Camber - he recommended "up to 3" degrees, fwiw.

[cvjoint]

I'll just put this out there:
"When tuning at reduced pressures use the following formula to determine the minimum safe pressure: Divide the total vehicle weight, including fueland driver, by 100 to arrive at the minimum safe pressure. Example: Your car weighs 2750 lbs. as raced. The minimum safe (cold) pressure is 27.5 psi." https://www.tirerack.com/images/pdf/warranty/HO0914.pdf

Per Hoosier's manual, 1,600lb Atom can be run on 16psi.

Given the manual info and accounting for passengers and uneven weight distribution I think 18psi is just fine, which is the TMI recommendation and makes sense to me.

[timcking]

I have a 2009 AA3 with 225frt/245rear Hoosier A7 tires. My auto-x venue went away, so I have lost much of my ability to dial in the camber. That being said, I've ended up with -2degrees frt/-2.5degrees rear and this seems pretty close. Pressure-wise I started with 15psi(c)/17psi(c) and have ended up with 18(c)/21(c). Along the way I talked over the phone with a Hoosier tech rep. He recommended pressures in the mid-twenties psi with a higher pressure in the front. I think cars like the Atom are outside their experience. If you have access to a track or skid pad, you can dial these in to obtain equal temps across the tires.

I recently ran an auto-x and started with 20 psi frt/24 rear (cold in 80 degree heat) which worked well. On my fourth run the tires "went off". Checking the pressures, they had risen to 24 psi frt/27 psi rear. I now know these latter pressures are too high. Just an FYI. I'm getting even wear with the above camber settings.