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Discussion Starter #1 (Edited)
SORRY FOLKS - I got a weird message when I tried to post this but apparently it worked, TWICE.

I've been autocrossing my 981 since 2014.<br>I added the GT3 LCAs this fall with camber at -2.8F, -2.5R. At the next autocross, a pyrometer showed even temps across the tire width - yeah! Unfortunately my RE71-Rs had no more traction after almost two years of AX (about the same thing happened with Sport Cup 2's).<br>
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I'd like to give Hoosier A7's a shot next year (and go to -3 camber). I have no trailer or means to haul my AX wheels to our site, which is 110 highway miles away. Rain/wet is extremely unlikely but I'm concerned that the street driving will use up/heat cycle out the A7's very quickly.<br>
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Does anybody have experience/knowledge of the impact of street driving on A7s?
 

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I know a lot of people that ocassionally drive Hoosiers to an autocross, but most live just a few miles away, not 110 miles. A7 are technically road legal when brand new (4/32 tread depth), but you'll have to stop before 1/32. They are near instant death in any standing water. The tread has a lot less puncture resistance vs street tires (lightweight) and pick up nails/screws/etc a lot faster than normal street tires. They'll also pick up every piece of gravel in those 110 miles and sling it against your paint. And worst of all: it will heat-cycle your tires and they'll wear out much more quickly. (Daily driving RE-71R & RivalS heat cycles them, too, but it's much less noticeable.)

You could drive home like this in an emergency, but I wouldn't recommend it routinely. Do you have a friend with the same club that has a trailer and can carry the tires to the events for you? I'd do that occasionally for out of town events when I was still running R-comps on my Boxster S.
 

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Or tow them yourself with a Leroy Engineering trailer, looks like a slick setup.
 

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Discussion Starter #7
Yeah, AX mileage is vastly different. My RE71-R's lost grip after roughly 58 miles of AX plus 5000 road miles over almost two years. There was still some tread left.

I'm hoping to find a trailer ride for my Hoosiers to the first AX. If not, I'll drive them. If I love the performance, I'll go the Boxster hitch and modified Harbor Freight trailer route.
 

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Discussion Starter #8
Reporting results of my Hoosier A7 experiment. I changed wheels at the AX site the first time around - a large pain given my other responsibilities. I had always run many of my runs with stability control on. That turned out to be totally unworkable with the Hoosiers. In particular, when I fed gas coming out of a turn, nothing would happen for a count or two - apparently the computer thought I had so much lateral G that I would lose it if power was applied. The corner traction and braking traction was wonderful.

The next event, I drove down with the Hoosiers on. In Northern CA, rain in the summer is almost unheard of, so I didn't have that issue. The tires worked fine on the road. Some of the Zone's hot drivers and the GT3 drivers missed this event - I ended up with top time of the day, Porsche. One of the Z06 Corvettes beat me. The tires are great fun, worth somewhere between 1 and 2 seconds I think.

I've now moved and will be running with SCCA folks, only 27 miles away but the last 300 yards is gravel. We'll see how that works on Sunday.
 

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I would recommend a steel bristle brush with a scrapper on top to remove the stones that get embedded in the soft rubber. I saw another A7 user put on a pair of leather gloves and do a sweep around his tires after each run to knock off stuff that they collected. I think I will give that a try along with the brush. I was running less pressure than I should have last event, including a 60 mile drive each way, to Packwood, Wa. I ran 31 psi on the road, with no issues. I do not have a trailer. Hoosier recommends 10 percent of cars weight with driver and gas. So 34 lbs as my new transit psi, then reducing to 32 for first run.

I can mention that the Hoosiers A7 are like qualifying tires, they stick very well, so what does that do to your suspension, well it brings out the best and worst in almost every aspect of how its put together. Hoosier's user manual suggests increase spring rates, shock valving, other structural stiffeners that prevent frame twisting or alignment changes. These slicks really ups your game, but are you ready for that challenge. My first outing on these remarkable tires was a mixed bag. I accomplished my goal for the event, moving into 2nd place in the overall class yearly standings, but along the way a lot of my gaffs were noted. The instructions say to drive smoothly, which I did not do. I tried to muscle the tires. I used the brakes too much, although no flat spots so the ABS was working overtime. I hit one cone during the two day event, so I basically stayed on course. For the next event, I will try to stay calm and drive smoothly and let the times slowly come down. The car balance was excellent, at no time did I really experience understeer or the dreaded oversteer. It's just that I stayed on the gas and took the car too deeply into the corners before turn in. So, I will try to use the Hoosiers differently, maximizing the G forces mid corner and corner exit, while looking much further ahead. Maybe even a different pair of shoes that are very flexible to give better input from the gas and brake peddle to my toes and feet. Thinking about better seats, buckets of some sort that will keep my hips and body secured without additional bracing.
 

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Discussion Starter #11
So now I have an A7 experience with 27 miles of street and 300 yds of gravel to my AX site. Not a problem. I looked for embedded rocks and really didn't see any. I have a "curry strip" that can rake off little rocks but don't believe that it's worth the effort in most cases. What I have learned is that spraying water on the tires can produce meaningful benefits. I'm running 42psi on the street, 33f, 35r on an asphalt course.

I can say that -3 camber corded the inside of my front street tires even though the middle and outside looked ok.
 

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were those pressures hot ?
 

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Discussion Starter #13
Street pressure cold. AX pressures are just before a run, so tires are anywhere from cold to hot.
 

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What front toe were you using to get inside cording on street tires? I run 5 minutes of toe out in front and -2.7 camber, and have yet to experience much wear on the inner shoulder of either fronts or rear on three sets of wheels/tires combo. Just saying what I see is the outside taking more of a beating from autocross/street driving than the inner shoulder. I have reversed the tires on the rims as well to even out the wear outside shoulder. I agree that running more PSI for the street is a good idea to help wear the middle of the tire, but I feel more comfortable with less, about 33 PSI f&r cold.

Talking with a Corvette owner yesterday at a PCA autocross track event, who got top time of the day, as he was removing his massive Hoosier A7's to his street tires. He showed me his slightly corded A7's (one tire) yet still said they will last him another couple of events. He had over 1000 road miles and a full amount of past autocross events, so a higher usage, lower wear ratio than I expected. Not sure how he stuffed four massive tires into his car for the trip home due to the threat of rain.

My take away is if you are going to use Hoosier A7's, fit the largest ones possible, yet retain some sort of f to r balance. For the price of these race tires, might as well maximize their tire patch and traction circle.
 

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Discussion Starter #15
My alignment for Hoosiers was with a local shop new to aligning GT3 LCA's. They reported F camber -3.29, -3.07, F toe at 0. R camber at -2.79, -2.84, toe at .06. My Pilot SS's for street use were fairly worn - not too far from the wear bars. I had to drive 1000 miles on pretty straight roads in my move to Tucson - you just have to look at the tires to see that they're riding on the inside edge. The rears were not corded, but they were worn a bit more on the inside. I should measure the heat distribution on the fronts to see if I really should have that much -camber for AX. I have reversed AX tires before, but these street tires were pretty evenly worn until I changed the alignment for Hoosiers.

The Hoosier documentation suggests 40-42 for our weight car, which clearly is too high for AX. On the street I've got all the traction I need at 42.

I don't know when these tires will fall off. My friends who run Hoosiers say their first couple of runs are the best, then they degrade bit by bit, then they're gone. My guess is they're good for 10-14 AX events. My experience is that when good tires fall off the cliff, the day is wasted.
 

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Hoosiers A7's Tech section on Care and Safety has a paragraph regarding rear engine cars as far as PSI goes. Independent rear suspension and rear engine, then the running point is 10 % of the total car wt, plus the wt of gas and driver. So, I figure that pressure is about 33 PSI at the autocross track. That pressure worked better for me this past weekend, than my first weekend event at 29 PSI. The lowest cold pressure for our cars is 27.5 PSI in the tech section. Travel for me requires a little higher pressure to get the center of the tire to work harder as the front outer shoulders still will scuff and the inner shoulder will be exposed to camber issues.

That Corvette really worked well on his Hoosier A7's eventhough they were showing some outside cords in front. He said that set will last for a couple more events as he was removing them. He was running -3.5 camber in front.
 

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Discussion Starter #17
ALIGNMENT CRAZIES. I took my 981S to a local shop that had never worked with Tarett LCA's and didn't have good access to shims. Instead of the camber specs I requested, they left me with -2.5/-2.4 F, -2.8/-2.9 R. I'd read in several places that you want the rears to have .3 to.5 less -camber than the fronts.

I took the car to a DE day with a new set of RE71-R's. It seemed to handle quite well, though I forgot to turn off PSM to check what it was really doing. I measured tire temps after 15 minutes on track and got F: 140 outside, 156 inside. R: 158 outside, 152 inside. I interpret this to mean that the rear setup is pretty good, using the whole tire surface. The front would seem to have too much -camber since the inside is getting more use than the outside. If I go with that interpretation I'd go with an alignment that has the fronts with much less -camber than the rears.

????ideas / comments???

In a week or so I'll run and measure my Hoosier A7's at AX.
 

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Wait until your autocross with the A7's before making any changes to your camber. I suspect that -2.5/-2.4 f is too little and you will scuff the outside shoulder a lot compared to the rest of the tire patch. I am at -2.7 f and still get scuffing on the outside shoulder of my A7's. Last race this past weekend until next season. The car is going into the shop in a couple of weeks for f camber increase to -3.0, corner balance, race alignment and Function First transmission mount install.

I transited to Bremerton on my Hoosier A7's about 30 miles each way without any difficulty. No rain or sprinkles on Saturday.

What do you know about Hot Lap II to reduce lap times of .2-.5 seconds and increase the life of qualifiers up to 50%, meaning Hoosiers A7's. Check it out, made by Kensers Pro-Blend. Hoosiers recommendation for storage is to suck out all the air in an airtight bag with a vacuum, for the winter in a 40-70 degree storage.
 

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Discussion Starter #19
I'm sure that my current alignment won't be the best for A7's. All of my A7 driving up to now has been with the fronts having more than -3. I'll report what I find during my 10/26-27 event.

Since I'm running a few DE's with RE71's and doing some road driving I'm looking for some kind of balance between the three uses. Longer life with Hot Lap II is intriguing - 3 good reviews on Amazon but nobody mentions tire life which seems difficult to measure.

I've just moved to Tucson where we run AX's all through the winter so I won't be storing the A7's. It's an SCCA group so I'm not really competitive - A7s are fun but I'm not sure that I'll keep buying them.
 

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I'm hoping for more than a year usage with A7's. That's 12 autocrosses and travel to the track and back. I'm going down that road, with stiffeners, more camber, more HP/Torque, but still being able to use the car as a daily driver with OEM wheels/Michelin MP4S's. I have another wheel set with RE71R's for autocross rain and a couple of DE's this next year. My M97 motor is about as protected as I can make it, deep LN sump, Porsche MotorSports AOS, Motol v300 Power 5W-40 oil, 996 GT3 oil/water heat exchanger and a 3 rd radiator. Just need to find a good set of bucket seats that fit with harness passthroughs. I bid on a set of GT2 carbon fiber seats with airbags, but was outbid on bring a trailer.
 
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