Rehash: 710's vs A6

[Steve Towers]

On Saturday afternoon my 710's went completely away, as in trying to guide a hockey puck. As you can imagine, Sunday was interesting (and slow). To the point, I'd value opinions re 710's vs A6's relative to the number of laps you can expect. I've read a slew of stuff on various forums, but I'm more interested in the experience of folks in our region that have run both tires. I've never run on Hooiers, but have gone thru 5-6 sets of 710's. The TireRack pricing is within a few dollars, so that's not an issue. Useful life is important. 3200 lb, rear wheel drive car. The most neg camber I can get in the front is -2.0, which is the current setup.

Actual experience will be more valuable to all of us than urban legend, e.g., "what I heard was.............."

I suspect this has been discussed previously on this forum, so if that's the case please direct me to that thread.

[Arthur Grant]

Steve what kind of car are you running and what size tire?

[Steve Towers]

[quote]by Arthur Grant on 25 Oct 2010 16:36

Steve what kind of car are you running and what size tire?

C5 Corvette, 2000 Hardtop. 275 fronts (8.5 wheels), 305 rears (9.5 wheels).

[Mako Koiwai]

We had to buy Hoosiers when Kumho ran out of our size for our C5 Vette. We've been pleasantly surprised at how long they've lasted ... but we're not camber challenged. -2 should be OK for you though? We would buy them again. I can't tell you how many laps, but we've been running them for the races since May ... but using our old 710's for Practice. Yah ... not ideal. So six races ... at least 48 runs, including 12 yesterday ... with Will K. doing 4 laps with our car in PAX.

That said, we might try Kumho's again next time ... using 275's up front like Rita uses.

[Arthur Grant]

We had to buy Hoosiers when Kumho ran out of our size for our C5 Vette. We've been pleasantly surprised at how long they've lasted ... but we're not camber challenged. -2 should be OK for you though? We would buy them again. I can't tell you how many laps, but we've been running them for the races since May ... but using our old 710's for Practice. Yah ... not ideal. So six races ... at least 48 runs, including 12 yesterday ... with Will K. doing 4 laps with our car in PAX.

That said, we might try Kumho's again next time ... using 275's up front like Rita uses.

What size are you using up front now?

[Steve Towers]

Wow, only 4 posts before this went off topic. Aaaargh.

[Mako Koiwai]

295/17

[Arthur Grant]

Why would you go back to 275? Do you feel your getting roll on the wheel?

[Mako Koiwai]

No, but Rita does. She feels the narrower, lower 275 turns in quicker and better ... but she's about the ONLY one that still uses a 275 up front on a C5 Z06. She tried a 295 Sat. afternoon and didn't like it ... again ... but she also didn't change her set-up from her 275 one ... if I recall correctly.

[John Fendel]

To the point, I'd value opinions re 710's vs A6's relative to the number of laps you can expect. I've read a slew of stuff on various forums, but I'm more interested in the experience of folks in our region that have run both tires.

I run a 3200+ lb Mustang in ESP trim.
I ran Hoosiers years ago, so my experience is dated. I was runnig 265/16 front and rear. I rotated the tires during the season so they lasted almost the whole season.
I am currently running Kumho 295/17 in front and 315/17 in the rear. The fronts consistantly last all season and a little into the next. The rears have two years on them and still have "tread". Both the fronts and rears heat cycle out before they wear out. I only run the CSCC championship events with extra runs at the CASOC practice.
I'm not camber challenged, there is plenty of adjustment available in the front, well over -2 degrees. Not so much in the rear with the live axle.
I hope this helps.

[Lisa Severy]

All I can say is the Hoosiers worked well on my C5 last Sunday...they really stick! I was also surprised to hear them "talk". The Kumhos are quiet.
My previous experience w/Hoosiers (on our Z-28) was similar - but they did not last long. There was one practice where Ryan, Bill Chin and I went to the cords on a set in the one day at El Toro... (which makes it a really expensive day).
My current plan is to save the Hoosiers for the Championship days and run the Kumhos for the practices. The Kumhos definitely lasted longer in the past. With Hoosiers- supposedly you can remount them and flip the inside to the outside to get even more use out of them. we'll see!
I have never had a chance to really do a fair comparison (run new Kumhos versus new Hoosiers on the same course). Bryan C has new Kumhos on his C4 and he beat Ryan in our C5 on the Hoosiers.
Has anyone out there compared the two on the same track on the same day? We always here Hoosiers are faster.

[Bob Pl]

I have run both the past year, same sizes, same car, same rims (well the aspect ratio is a lower number on the a6, so not EXACTLY same size).

New to new the a6 is faster, by at least a second to a second and a half. It is made with softer compound.

The a6 will cord in fewer laps, lets say 75 laps vs. 100 on 710. These are not absolute numbers, just a comparison so if anyone posts that they corded their a6's in 25 laps or got 200 runs out of their 710's ignore them.

This makes the a6 more expensive even at the same initial price, right? Fewer runs same price.

Because a6 has softer compound it requires more camber or it WILL cord the edge. 2.0 is probably not enough IMO.

New a6's are always fresh tires, new 710's may have sit in a warehouse for 2 years.

Both heat cycle out before they wear out.

Hoosier is an American company that makes race tires. Kumho is a Korean company that makes race/truck/bus/tractor/car tires.

I still use both.



Hope this helps.

[Jason Isley BS RX8]

No, but Rita does. She feels the narrower, lower 275 turns in quicker and better ... but she's about the ONLY one that still uses a 275 up front on a C5 Z06. She tried a 295 Sat. afternoon and didn't like it ... again ... but she also didn't change her set-up from her 275 one ... if I recall correctly.

Have you noticed how tall the 295/17 Kumho is compared to the 295/17 Hoosier? The Kumho has a massive sidewall that takes for ever to load up after you turn in. It also weighs as much as a 315, it is a pretty useless size.

For Steve's purpose a 295/17 front is not really an option, with his wheels size 275/17 is about the useful max. The question becomes the rear... The V710 is a good rear size for an AS C5 (305/18), with the Hoosier you have the smaller 295/18, or pinch a 315/18.

[Steve Ekstrand]

@Mako----WWBPD

What Would Brian Peters Do?

[Jeff Wong]

New to new the a6 is faster, by at least a second to a second and a half. It is made with softer compound.

Seems like a lot of time...

[Aaron Goldsmith]

New to new the a6 is faster, by at least a second to a second and a half. It is made with softer compound.

Seems like a lot of time...

Nationals SS results show them to be fairly equivalent with top tier drivers. Hoosiers perhaps having a slight edge. We go with who rewards with contingency.

[Bob Pl]

Here we go again.

The OP asked for real personal information/observations which is what I posted.

I specifically responded with exactly the personal information he asked for.

You want to base the tire choice on SS Nationals results?

The official 2010 SS Open results lists 62 entries.

Only ONE ss car lists Kumho for tires. It's a Corvette.

The first CORVETTE (finished 3rd) combined time (Hoosier) is Dietz 118.541

The only car on Kumho is a CORVETTE (finished 52nd) combined time is Strope 125.128

Of course the drivers are not equal, but that's all the data there is & it's 6.6 sec difference combined of the best runs scored.

Too small a sample size (Statistics 101) comes to mind.

That's a "lot of time", yeah.

I don't even know how you can come to a conclusion "fairly equivalent with top tier drivers" with ONE driver out of 62 on Kumho? ONE driver?

Here's a link to the results.


http://www.scca.com/documents/resultfil ... 20file.pdf" onclick="window.open(this.href);return false;

AS is an even smaller sample size.

[Arthur Grant]

Have you noticed how tall the 295/17 Kumho is compared to the 295/17 Hoosier? The Kumho has a massive sidewall that takes for ever to load up after you turn in. It also weighs as much as a 315, it is a pretty useless size.

I don't think the 295/35/17 Kumho is a useless size. For those of with multiple sets of 9.5" wide wheels the 295 represents the widest tire we can fit on that wheel. For the back of a torque machine like my C4, the 295's make great rear tires, and if I want to square up decent fronts. Would prefer a lighter tire, but since I am not going to be running for a championship in the next couple of years will trade wear for a touch more speed.

The issue for me are the comments on camber. The Vette is camber limited (about 1.7 degrees) so it may be the Hoosiers are not as suitable.

[Jason Munchhof]

Here we go again.

Bob, I'm going to guess that Aaron was referring to National events, not just the championship. Dietz ran Kumhos for most of the year (SD tour, El Toro, Wendover) and was plenty competitive on them. They're certainly not 1-1.5 seconds slower.

FYI, I got about 85 runs out of my last set of A6 and they weren't yet corded... after about 60 they are pretty useless on lower grip surfaces, but still work pretty well at El Toro. They definitely need to be flipped in the 30-40 run range.

[Aaron Goldsmith]

Here we go again.

Bob, I'm going to guess that Aaron was referring to National events, not just the championship. Dietz ran Kumhos for most of the year (SD tour, El Toro, Wendover) and was plenty competitive on them. They're certainly not 1-1.5 seconds slower.

FYI, I got about 85 runs out of my last set of A6 and they weren't yet corded... after about 60 they are pretty useless on lower grip surfaces, but still work pretty well at El Toro. They definitely need to be flipped in the 30-40 run range.

Yeah pretty much. All the former Kumho drivers seem to be pretty competitive on them.

Though concrete and lack of contingency seems to have changed the dynamics some.

Data AQ shows the same general setup works for both and that they are fairly close in overall grip. They feel different and and they fall off differently.

[Mark Duerst]

Bob

Both Jason's make some good points here. First off this is not a Z06 but a 2000 C5 hardtop. It has different size rim widths and camber adjustability than your Z06. National level racing is a great indicator since the cars in SS are set up for the most part very similiar,and there are good drivers who have run both tires.

[Jeff Wong]

Here we go again.

I don't even know how you can come to a conclusion "fairly equivalent with top tier drivers" with ONE driver out of 62 on Kumho? ONE driver?

Damn BP, when did you become such an E-Thugger? :gpower:

[Aaron Goldsmith]

Here we go again.

I don't even know how you can come to a conclusion "fairly equivalent with top tier drivers" with ONE driver out of 62 on Kumho? ONE driver?

Damn BP, when did you become such an E-Thugger? :gpower:

I was wondering the same thing, haha

[John Stimson]

New to new the a6 is faster, by at least a second to a second and a half. It is made with softer compound.

I won't take issue with anything else, but that's just plain not true. I've run both tires on my own car in identical sizes and did not find a large difference in how well I did on one compared to the other. My only National Tour win in my own car was on the V710s. I've watched multiple seasons of local competition between SS Corvettes in a deep talent pool, some on the A6 and some on the V710, and there is not 1 second worth of difference between their times that could be attributed to tires. One of the fastest guys ran V710s that he drove 30+ miles to and from events on, and kept on the car past 100 runs. I'd say the difference is worth a few tenths of a second at most.

[Bob Pl]

Well now we are getting more posts based on personal experience/results, that's a good thing and what OP asked for.

The a6 is that much faster for me on my car, maybe I can't get as much out of a 710 as others can, maybe a 275 710 is better than a 295, I usually buy 295.

I can't read minds, so if someone posts an opinion that contradicts my experience and then bases his argument on irrelavant data what is the "correct" response, so I won't be accused of E-Thuggary?

I'm really trying to work on my forum posting technique.

:gpower: