Being able to retain and build more heat in the rear 275s might have contributed. Gotta keep the tire hot, but not too hot and over-saturate it.

Also in autocross it is imperative to build heat in the tires as quickly as possible since the runs are so short. A big cold tire will usually not perform as well as a smaller, warmed up tire.

I would agree with this, my rears were not helping until the 4th run. Then it shat and gat...

I think it was two main things, the feel of the 275 RE-71Rs , and this seems to be agreed upon by all who have tried them, is amazingly direct. No squirm like I experienced in both the Rival and the Falkens. Part of that feel may have been the 275 on a 10.5 inch rim vs the Rival 315 on a 10.5 inch rim, but it may also just be the tires personality. The other reason is compound. The RE71R is softer, even though both are rated at 200 TW. I see more wear on the RE71R than the Rival. Oh and both these tires felt pretty darn good hot or cold...

Makes sense.

Yeah I'm currently opening up the rear tubs 1.5" (on the outside) to fit wider tires. Just wondering if I'm wasting my time! Ha. 275's square have done well on the car, though looking forward to trying more tire. I should have some data from the road course come this fall.

Tom -- another reason why the difference in performance with the 315s in the rear... vs a square setup (275x4)... could be that the 315s are a touch taller in diameter.. thus shifting a bit of weight towards the front of the car (changing the balance that you're used to)... and actually changing the alignment slightly by reducing the positive caster (having taller rear tires lifting the rear).. from whatever/whenever you had it aligned at. When you had the alignment done, did it have a square tire setup? (all 4 tires the same size/diameter?)

Mitch, could be, although I lowered the rear an inch right when I tried these two sets. The 315 Rival S just didn't feel as glued down in the rear, the front felt good (with the Bridgestones). When I had the alignment done I actually had an even taller rear tire, the 305/30/19 Hankook. Wade I think right now with the current crop of 200TW tires you don't need wider than the 275 RE71R, but this tire war will do nothing but escalate. Someone is bound to bring out a wider super sticky tire. If I were to build a car from scratch I'd aim for a 18x11.5 315 front and a 18x13 335 rear, and I'd run the Rival S on it for now...

The RE71R's must warm up in the first turn basically. Autox and Road course duty are different requirements for a tire, that is for sure. Rivals may be a better "overall" tire in that dept.

Any reports yet on how the RE71R hold up on the road course? Sounds like a great autocross tire, just curious how they hold up with more heat.

The current tub work should clear 305/30/19's or maybe 315/30/18's, but no more. My 'goal' is to stay square (or as close to it as I can). We'll see what the front will do after I try your bottle jack mod . I need to sell some of these 18x9.5's and start looking for some 18x11's and 19x11's. You mentioned 18x11.5's for 315s- any specific reason? Looks like the 'measured width' wheel is 18x11 - just curious if you had a reason.

Tom- what's your current 200+ tw tire ranking now?

Guess:
RE71R
Rival S
RS-3
Star Spec
...
...
...
...
super sport

?

Wade send me some pics of you wheel stock, you can currently get a 285/35/18 in RS3 V2's. I could rock that as a square setup on 9.5's...

I like the 11.5 just because it would push it out a little more, trying to get every last MM out of that tread width... In Japan the RE71R comes in a 295/30/18, which would be the best of all worlds, a square setup on 18x11s with those would be my first choice for the Valiant. Realistically though I can't imagine anything being much faster than these 275 RE71R on the 10.5s all around. I'm having trouble trusting the car to the limit since it's so far past what I'm used to. You can see in the pic below the 275 RE71R on front and the 315 Rival on rear...

Current Autocross ranking for 200 TW tires:

Bridgestone RE-71R
BFG Rival S
Dunlop Z2 Star Spec
Hankook RS3 V2
Dunlop Z2 non star spec
"New compound" Falken RT615K
Original BFG Rival
Dunlop Z1
300 Treadwear Michelin Super Sports.

I would move the Hankook up above the Z2 star spec if it's really hot, and down below the Falken if it's very cold. I would move the supersports up the rankings for a track day where I'm running lots of laps in a row. There are the new Toyo R1R and Kumho V720 coming out, rumors put them near the Hankook, definately not Re-71R or Rival S fast...

Wow, hyundai is proud of those kits. $242 seems like a lot to me for what it is. I've always put them on under warranty so i never looked at the price. ..

Thanks for the info, Tom.

Emil-
2 sets of gt500 wheels. 18x9.5 +45mm
1 set of enkei pf01's. 18x9.5 +38mm

zoiks! Thanks Chris for trying, I have an old Fram canister fuel filter I'm gonna rig up.

For a rear end breather? I run this one from Art Morrison. $45.

http://www.artmorrison.com/layout.php?y=store/&x=new

We took $1 store aluminum water bottles, flattened the plastic cap, JBwelded the threads to seal them, tapped the cap 1/4"NPT for a nipple and put a breather in the other end of it.

We were down to ~$3 or so for an "aluminum catch can". Kinda hard to see, but if you put a sticker on it, it makes it look like a $20 catch can.

Just figured I would share my axle vent solution. Had some scrap around.

Well done Emil! Thanks for posting the video. It was fun to ride along. Did you consider running CAM instead of ESP? Looks like your times were closer in CAM. Keep up the good work!!

I would have but my rear tires are 100AA. My front are 300AA NT555's but 300-100 doesn't get you in a 200AA tire class lol. My times are what they are no matter the class anyway. I plan to have CAM legal rubber next year and I will be back. Plus I have a fueling problem that raised its head that day and comes and goes ever since, its either the pump,relay or both.