[VR Baron]

Originally Posted by WishfulSS

I spoke with a driver who goes to nationals at a national tour event and he said he was running 32/31 f/r. Next weekend I will post pyrometer temperature profiles at 33/32 and 32/31 after I get the 305/30/19s mounted on the rear. Running stock suspension with recommended Chevy of -2.0 frontand -1.5 rear camber with minimum toe.

Sounds good. All in the range depending on wheel size and the rest of the setup. 31-35 seems to be the range, like other tires. My camber is at -2.8/-1.8 , so that, the wheels and the bar makes a difference. She likes 33,34 and will try 32.

Also watch psi and any possible “grove of doom” excess wear on the outside edge of the second tread block. It wears a lot faster but May not make a difference depending on when the tires cycle out

[clyde]

FWIW, with 285s all around, currently running 36/35 f/r and dropping a bit front or rear for balance specific to the day's course and happy.

For every tire I've run on the car, once in the basic ballpark, the front rear split has seemed to have a much greater impact than the actual numbers.

[VR Baron]

Originally Posted by clyde

FWIW, with 285s all around, currently running 36/35 f/r and dropping a bit front or rear for balance specific to the day's course and happy.

For every tire I've run on the car, once in the basic ballpark, the front rear split has seemed to have a much greater impact than the actual numbers.

I ran the first event at our summer venue on Sunday. Lot isn’t as grippy, has elevation changes that aren’t mild for a parking lot, drainage culvert to drive across diagonally and long huge rough and raised patched areas. Fun but probably worst case for an autocross venue. I ran 32/30 cold psi and just let the psi rise through four lap sessions that were 50 seconds for a fast course with decent 180 turns out big cars could handle save for a few tight ass turns and gates. The pressures in four runs went as usual to 34/32 or 2 psi increase except the left front that went to 36 as that was the tire taking the brunt of the force on this course’s direction. The Re71rs tires did great and I felt total confidence in them in that they could be pushed with no issues until you couldn’t. And that happened on some runs…lol As usual these tires take to runs to get warm per the dash readout, though I don’t push it on the first lap then gradually turn it up so goi g all out on runs 3/4, which are pretty close time wise.
This course size and design and starting at the lower psi vs using the hot pressure to start finally got the scrub area to the arrow tops as before they never came close. These tires sure do have a stiff wall when slightly stretched!

The other thing I changed was for the first time I used comp mode vs all off with track mode and mag and steering set to sport for the rough surface.
Combo did great, comp mode with some stabilitrac for keeping the rear in place kept the car glued, a friend in track all off with his zl1 was losing it in a lot of places.

Well that’s it. These tires do great, really peak out at 34/35 hot, grab like hell
And are wearing really well.

[WishfulSS]

So I went out last weekend with 285 F and 305 R. There were 106 on Sat and 76 on Sunday. I was checking tire temperatures with a memory pyrometer where you stab the tire with a thermocouple. I was in the first run group both days with about 75-80 F ambient on airport concrete. five runs each day with getting temps from the last four or three runs. I was trying to get to even temps across the rears. Seems like going up to 35 psi in the rear was more even.
Saturday
CCW Outside L cntr Inside inside cntr Outside Right
33-32Front101 100 89 110 107 105
Rear 106 104 109 111 113 105
75-80F
33-32Front103 101 102 111 110 107
Rear 108 102 103 110 100 106
63.8 sec
33-34 Front 106 106 104 104 107 113
3rd/31st Rear 104 107 108 107 109 109

33-34 Front101 100 99 112 113 106
Rear 103 103 109 107 102 103

Sunday
CW Outside L center Inside inside center Outside Right
75-80F Front
2nd/24th Rear

33-33 Front 102 102 104 98 96 94
68.9 Rear 109 107 109 106 100 99

33-34Front 107 107 107 103 102 98
67.9 Rear 112 108 111 113 106 104

33-35 Front 112 111 109 103 101 99
67.4 Rear 114 113 114 107 107 105

For even temperatures I like the 33 F and 35 R. That was my fastest time on Sunday but with two cones. I will continue with the temperatures next autocross.

[JamesNoBrakes]

I did much better this weekend with 1-2psi more in the front as compared to the rear. Square 295s.

[WishfulSS]

Originally Posted by JamesNoBrakes

I did much better this weekend with 1-2psi more in the front as compared to the rear. Square 295s.

My BMW M3 3100 pounds 225/45/17 F 245/40/17R +3-6 psi in front. With 245/45/17 F+R stil +3 psi front.

2020 Mustang Ecoboost HPP/HP 3600# 285/35/19 F+R +1 psi front (32/31)

But both of them had pretty uniform temp across the rears with fronts having higher on edges. Both had less front camber than the Camaro. The temperature information is not clear yet.

[VR Baron]

Originally Posted by WishfulSS

So I went out last weekend with 285 F and 305 R. There were 106 on Sat and 76 on Sunday. I was checking tire temperatures with a memory pyrometer where you stab the tire with a thermocouple. I was in the first run group both days with about 75-80 F ambient on airport concrete. five runs each day with getting temps from the last four or three runs. I was trying to get to even temps across the rears. Seems like going up to 35 psi in the rear was more even.
Saturday
CCW Outside L cntr Inside inside cntr Outside Right
33-32Front101 100 89 110 107 105
Rear 106 104 109 111 113 105
75-80F
33-32Front103 101 102 111 110 107
Rear 108 102 103 110 100 106
63.8 sec
33-34 Front 106 106 104 104 107 113
3rd/31st Rear 104 107 108 107 109 109

33-34 Front101 100 99 112 113 106
Rear 103 103 109 107 102 103

Sunday
CW Outside L center Inside inside center Outside Right
75-80F Front
2nd/24th Rear

33-33 Front 102 102 104 98 96 94
68.9 Rear 109 107 109 106 100 99

33-34Front 107 107 107 103 102 98
67.9 Rear 112 108 111 113 106 104

33-35 Front 112 111 109 103 101 99
67.4 Rear 114 113 114 107 107 105

For even temperatures I like the 33 F and 35 R. That was my fastest time on Sunday but with two cones. I will continue with the temperatures next autocross.

I am not to surprised on liking more rear psi with 305s on I assume 11” wheels. These tire run a bit wide and maybe on the more squished side so more rear psi will even things out some. My 305 Nankangs ran wide and a softer wall and liked 2 psi more in the rear to be more neutral and more equal heat, showing they were working more as they should vs the front. The fronts were fine as I had max camber and a bigger front bar to control rollover. For my 285/35/19 sq on the same 11” wheels and are a bit stretched, and Nannie’s off, 34/34 is a bit oversteer biased out of corners if you don’t watch it, 34/32 works great and the car is planted.

[Msquared]

I tried out the 285/305 combo at a local event yesterday for the first time. First thing I found is that if you try to drive with all the nannies on, it isn't happy with the "reverse stagger" in diameters. It engages traction control and severely curtails acceleration. Not a big deal really, because if you just turn the TC off it's no longer a problem. I think you could just do the quick press of the button to solve it, but I didn't mess with that: I did the whole 5-second push to turn off all the nannies. I fully expected this, and I always autocross with all nannies off. The only annoyance is that you can't run cruise control with the nannies off while driving to/from the event.

On course, everything worked well. As Apexit wrote, I got the ice mode brake pedal twice on one run, but the other five runs I did not. It could have been a anomoly, or it could be more prone to do that with this reverse stagger setup. I have occasionally found ice mode with other tire setups on this car, maybe a couple times a season, so it's hard to draw causal relationships here. I do think that if I had a 16-18 1LE I might not take the chance on this tire setup, because those years are more prone to ice mode. The tires handle well and I put in very good times, so I am ready to call this a success.

That said, if Bridgestone would make a 285/30 I would opt for that up front. Hey, Bridgestone: hint hint!

[WishfulSS]

I am running stock wheel widths of 10 and 11 inches. I did not get ice mode these two events but I have twice this year on a 285 square setup. Seems to come on during maximum braking just when I turn the wheel and (slightly) overload the fronts. Then the ice mode came on. I have not gotten it if I decrease from max before turning.
I second the request for 285/30/19s. Or 305/35/19s.

[DaveC113]

Unfortunately not FS legal, but the 305/30/19 would go well with the 295/35/18 up front, which is .2" shorter.

Also, it's possible to run 305/30/19 square on FS-legal wheels, you can fit 305 on 10s. Why not just do that instead of running the taller 285s up front?

Increased chances of ice mode would be a no-go for me, even with a '19+ ABS module.

I already have a set of 18x12 square, would be nice to also get 19x12s, but funds aren't unlimited. Now that the 305/19s are out I'd rather run them but oh well. 295/35/18 works pretty well.

[Msquared]

Originally Posted by DaveC113

Also, it's possible to run 305/30/19 square on FS-legal wheels, you can fit 305 on 10s. Why not just do that instead of running the taller 285s up front?

It is quite possible to run many 305/30/19s on 19x10 wheels. It is a massive struggle to get this particular model of 305/30/19 to mount on a 10" rim, though. Most of the successful mounting attempts have been done after the tires are run on a wider rim or are "heat cycled" at Tire Rack (which turns out to be running them on a roller with a load) - things that will "break in" the carcass to make it a little less stiff. This particular 305 has been show to be wider than 315 Hoosier A7(!), and its carcass is incredibly stiff. Also, the RE71RS seems to like to be stretched, and I'm not convinced that this 305 on a 10" rim would be faster than 285/35/19 on the same wheel. In fact, I seriously considered going with their 275/35/19 for my fronts.

I'm not against using a 305 on a 19x10 in general. In fact, I did just that with the Falkens, and I know lots of people used the RE71R that way too. I just don't think it's a good fitment with the RE71RS.

[DaveC113]

Originally Posted by Msquared

It is quite possible to run many 305/30/19s on 19x10 wheels. It is a massive struggle to get this particular model of 305/30/19 to mount on a 10" rim, though. Most of the successful mounting attempts have been done after the tires are run on a wider rim or are "heat cycled" at Tire Rack (which turns out to be running them on a roller with a load) - things that will "break in" the carcass to make it a little less stiff. This particular 305 has been show to be wider than 315 Hoosier A7(!), and its carcass is incredibly stiff. Also, the RE71RS seems to like to be stretched, and I'm not convinced that this 305 on a 10" rim would be faster than 285/35/19 on the same wheel. In fact, I seriously considered going with their 275/35/19 for my fronts.

I'm not against using a 305 on a 19x10 in general. In fact, I did just that with the Falkens, and I know lots of people used the RE71R that way too. I just don't think it's a good fitment with the RE71RS.

Yeah, I've heard mounting the new REs can be very difficult and even worse pinched.

On heat cycling, I didn't do it on my current set and regret it... 1st few runs were really bad, on the heat cycled set they seemed to not need as much scrub-in.

I hope they make the REs in 315/35/18, the 295s are good but 315>295.

[VR Baron]

Originally Posted by Msquared

It is quite possible to run many 305/30/19s on 19x10 wheels. It is a massive struggle to get this particular model of 305/30/19 to mount on a 10" rim, though. Most of the successful mounting attempts have been done after the tires are run on a wider rim or are "heat cycled" at Tire Rack (which turns out to be running them on a roller with a load) - things that will "break in" the carcass to make it a little less stiff. This particular 305 has been show to be wider than 315 Hoosier A7(!), and its carcass is incredibly stiff. Also, the RE71RS seems to like to be stretched, and I'm not convinced that this 305 on a 10" rim would be faster than 285/35/19 on the same wheel. In fact, I seriously considered going with their 275/35/19 for my fronts.

I'm not against using a 305 on a 19x10 in general. In fact, I did just that with the Falkens, and I know lots of people used the RE71R that way too. I just don't think it's a good fitment with the RE71RS.

Yeah they are stiff. It took 100 lbs psi after warming them in the sun to mount 285/35/19s on my 10.75” wide wheels. But they handle great and grip as well as 305/30/19 nankangs that are wide as well with about 1/2” more tread on the ground. With the hotchkiss front bar set soft , and on a fast course the less abused side tires are still not quite to the arrows with 34/32 psi. Probably start lower next time

[Msquared]

Originally Posted by DaveC113

On heat cycling, I didn't do it on my current set and regret it... 1st few runs were really bad, on the heat cycled set they seemed to not need as much scrub-in.

The day before the first autocross on these tires, I put them on the car and went for a drive on a hot summer morning. I went to "research park" that has no traffic on weekends and did some slightly spirited cornering, accelerating, and braking, trying to work the carcasses and generate some temps without ever sliding in any direction. A cop or Karen would disapprove, but it was nothing like an actual autocross run. Then I gently drove home and parked the car until the next morning's event.

I'm hoping that helps stabilize these tires and gets a little more usable life out of them. The 285 square set I used last year fell of a cliff in terms of grip, to the point that I wondered if either my car or I were malfunctioning. Mike (Apexit) saw my times at the St. Louis CAM Challenge (he won CAM-C...in an FS-legal Camaro!) and probably thought the same thing. But based on last Sunday, it was just the tires.