Kumho V720 ACR viper tire..
 

Any tried running the 295 25 19 ACR Viper front tire on the front
and the 305 30 19 non viper tire but could have shaved and heat cycled just like the 355 30 19s that come on the rear of the viper

179.00 fronts
241.00 rears

179.00 sq setup?

I have talked with my guy at the tire rack

He flat out said do 295 square. Said its Magic!

That being said I dont have the money to be testing all the new tires this year.

I would love to test this Vs what to me is the benchmark for me, the RE71R.

Also with the new falken out soon in a 315/30(eta is summer on those)

295 25 19 - now showing $238 each


https://www.tirerack.com/tires/tires...=925YR9V720ACR

I know Colby Shield runs the ACR tires 295 square on his SS 1LE in Gridlife Time Attack, they're faster than an RE71R.

ebay free ship to 179

The Viper version of the V720 is a different compound than the regular V720. The regular V720 really is only made to sustain up to autox demands, not track demands. Kuhmo has even said this before and I can attest that the regular V720 do not hold up on track (on lighter cars than the Camaro).

Outside of that, I thought for most 200tw competitions the Viper version is on an exclusion list?

i always here about this list but have never seen it! lol

Yes the ACR tires are illegal in almost every 200TW class

autocross wise yes.

Right from the SCCA Time Trials Rule book

E. The tire must not appear on the following exclusion list, which may be altered at any time by the Time Trials Board (TTB) upon notification of membership.

- Kumho V720 ACR (less than minimum molded tread depth)

I was about to say, I thought the Kumhos were illegal for autox because of tread depth. I've certainly never seen anyone using them

They aren't specifically listed in the SCCA Time Trials list, but the way their tire rules are written make them illegal:

The Viper versions are 6/32, they are "variations differing from standard specification", and are only offered in two sizes.

Now, why Kumho decided to use a different (much, much, much crappier), autox-specific compound on their regular version is beeeeeyond me, as if their normal was anything close to what the Viper version was, they'd be selling a lot more.

I am running 305 RE-71's in the front and the 355 Viper Kumho's in the rear, it is the best grip i have had so far and I have ran a lot of different sizes in my short 1800 miles of ownership.
305/30R19 front
325/30R19 rear

285/35R19 front
285/35R19 rear

305/30R19 front
305/30R19 rear

325/30R19 front
325/30R19 rear

305/30R19 front
355/30R19 rear

What rim do you run the 355s on? And the dimensions and offset? Any spacers?

Stock 19's, rear camber is at about -2.2 and the wiring harness is relocated in the left wheel well.

Yes they are specifically listed on the SCCA Time Trial Exclusion list. I copy and pasted right from the page.
Kumho probably isn't making the other tire sizes in the ACR compound because it clearly isn't a 200TW. That's the real reason most competition groups are excluding them. They are the ultimate 200TW cheater tires. The tread depth/size availability is just the politically correct way of excluding them.

355's ACR's on stock 19's with -2.2 rear camber

Nice!

They do just hit the inside lip of the fender during really hard compression though, I just put a few layers of xpel tracwrap on the edge of the fender.

What fronts do you run with them?

305 RE-71r'S

Any room inboard if you went with a higher offset than OEM?

My bad. I mis-read and thought you had posted about SCCA Solo.

You think tires like the RE71R and A052 are really any different in the mentality you state? This is and has been the big topic with these tires* for the past few years in the autox scene... The A052 basically went through the near-exact exercise: Yokohama took one of their "streetable track tires" that could meet the 200tw "rating", making a little adjustment to the compound, increasing tread depth and keeping essentially the same tread pattern.

Pre-2019 A052
"Streetable Track Tire"
TW: 200
TD: 6/32"
TP: https://www.tirerack.com/images/tire...pdp124crop.jpg

2019+ A052
"Extreme Performance Tire"
TW: 200
TD: 7/32"
TP: https://www.tirerack.com/images/tire...pdp124crop.jpg

ACR V720
"Streetable Track Tire"
TW: 200
TD: 6/32"
TP: https://www.tirerack.com/images/tire...pdp124crop.jpg

Mainstreme (post ARC) V720
"Extreme Performance Tire"
TW: 200
TD: 8/32"
TP: https://www.tirerack.com/images/tire...pdp124crop.jpg

ACR V720 version + 7/32" + more sizes... why not? Kumho essentially dug themselves into a very specific corner (regional-level autox) with their mainstream V720.


*"these tires" = the recent top "extreme performance tires"

I would like to think you could move them inboard 1 or 2mm but when I pulled the wheels off before winter I thought I remembered very slight rubbing on the fabric liner that must happen during compression, I will hopefully uncover the car next month and try to take a picture of this.

I don't think they are much different as the RE-71 was the original cheater tire, but it has become accepted. I still think the ACR compound is different. Why else would Kumho say you shouldn't track the new V720 compound, but the ACR was made to set track records?
Isn't the Yokohama under review for being legal?

Oh, I agree with you: the regular V720 has to be different than the ACR V720. I have never heard of anyone with chunking, de-laminating, and/or separation issues on the ACR version like people do with the regular V720. I know some people claim that they have run the regular V720 on track with no issues but I have personally seen quite a few different people run them in autox and several people in Lemons or track days have issues with them. They have good pace, but severely lack the durability. Sad because the old Kumho tire from late 2000's/early 2010's was awesome (forget that tires name XS-something).

The Yokohamas were under some review, but last I read (end of last month), the case has been dropped.

I also saw the pirelli corsa pcz4 305 19a for dirt cheap

Will it mess with stability track having the 355s on rear and lets say the the 295 vipers on front?

https://www.roadandtrack.com/motorsp...rburgring-lap/


several came apart at Nuremberg. I think the Khumo track tire was made to make fast laps on the ACR here state side but not "raced" if that makes sense.



I didnt think shaved tires were legal in any SCCA street tire class guess I was wrong.

Yes those viper fronts are stupid short, at 295/25, they would really piss off the stability track.