R6 vs A6

[TowDawg]

I know this has been discussed before, but after some more reading, I wanted to get some people's perspective that have run both on road courses.
I know the A's are stickier and get to temp faster than the R's, and because of that, they also get greasy faster after longer runs. I have been running a set of R scrubs, which are a HELL of a lot better than my Invo street tires, even with a ton of heat cycles. I had the outside of the driver and inside of the passenger side front tires separate this weekend at Road Atl. They weren't corded, but they were worn pretty good and the temps got down into the 20's Sat night, so getting up to temp from that probably didn't help. I noticed it during my "pre-run inspection" on Sunday, so luckily nothing bad happened. Even though these were used tires, I still got 21 sessions (30 mins each) of them, which I'm perfectly happy with. Yes, I could tell they were losing grip, but they were still much better than my street tires. I'm just running HPDE's and not competition, so some lost performance wasn't the end of the world.
All that said, apparently the the R's start losing their "full" effectiveness after 8-10 heat cycles. They probably had more than that when I got them and was thrilled compared to street tires. From what I're read about the A's, they tend to start losing grip sooner during the session because of heat, but they start losing it in a very progressive manner that is easy to manage, and they tend to make it back to full grip for far more heat cycles than the R's. I also read that the A's aren't as bad about overheating on longer tracks than I originally thought.
Even though these tires were shot, I still got a new personal best at Road Atl of 1:38.70 on Sat morning. The new 5th gear ratio made a huge difference for me down the back straight. I can only imagine what it feels like to run on new Hoosiers.

So for those of you with experience for both, is the info I read above pretty accurate in terms of how long, predictable, heat cycles, etc the A's vs R's are?

 

[steve911]

I run A-6's at Road America, Gingerman, Autobahn, and love them. The only time they started feeling the least bit greasy was a day at Autobahn where ambient temps were near 100 degrees. I can only imagine what track temps were.

 

[Allan]

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[bluestreak]

If it's hotter than about 85 ambient, A6's will get greasy pretty fast. The rule of thumb for many competitors is if temp is >85 run R6, <85 run A6. If there is cloud cover, you may be able to adjust up 5* and use the a6. A6 are not the two lap wonder people thought they were, but they do have their limits. I personally have gotten 24 HC out of a set of A6's, albeit about 60% of them time trials with 3-5 lap sessions. They were still running low 1:28's at Road Atlanta when one of them split from me using too much of the gator. Could have gotten more HC's. The key to longevity is not to over heat them If you feel them getting greasy and keep pushing, they will turn to trash. If you back off a bit or do a cool down lap and let them come back, they will last a good while.

A6 and R6 are pretty similar, dynamite grip on the very FIRST session, fall off a tad (about .5) from there and then hold steady. R6 for about the 8-10 A6 about 6-8, then fall off a bit more ( about .5-.8). Here's the thing though, if you care for them properly and don't leave them sitting on the car over the winter, they will hold pretty steady to the cords with only very small increments of speed lost. As they age though you have to be more patient with them, they need some laps to get the magic back, especially at the beginning of the event. People who like to blame tires for them being slow will toss them after that first slide session not knowing that is bringing them back. Many many many people are running A6's to the cords and still going fast on them.

 

[TowDawg]

Thanks guys. I like that Steve didn't have too much of an issue in the warmer temps. The vast majority of the tracks I'm going to be at are going to have higher temps since they're in the south. However, with NARRA being at RA earlier in the year, and that being the main time I plan on tracking the Viper after I find a dedicated track car, the A's would probably be fine. It may come down to what I find a better deal on. I now have a brand new A in 275/35 that I managed to buy from someone at the track when the first one of my R's split, so I might keep it and run 275's on the front, or I may sell it and look for 295's again. Anybody have a guess what it might be worth? It went on my car brand new and only has one 30 min session on it (and that session was run in an ambient temp of about 55 degrees, and on the passenger side, which doesn't see a lot of abuse at RA).
And Blue, what the hell are you running 1:28's in? That's fast Viper Cup car times! I would love to lap that fast. Considering how old my R's were, I would think I could possibly get to 1:35''s or 36's with brand new ones. I was just so happy with how they performed compared to Invo's, that I can't imagine how new ones would feel.

 

[bluestreak]

I've run the A's in hot temps as well, they just aren't as good. They are spectacular in cooler weather. Probably equal to worse than R6 in hotter temps which is why people run R's in the summer. I have a Porsche Turbo that is a dedicated Time Trial car. It's gutted, aero etc. Ran a 1:27.1 in March on A's.

 

[treesnake]

I was at RA the week before TOWDAWG. So track conditions were similar for comparison. I was rotating a set of R6s with a set of A6s.....
I do want to say that the R6s were 315s and the A6s were 295s. Also, this was my second event at Road Atlanta... That being said, I was experimenting with different track lines and braking points. My lap times varied from 1:40 on Sat. to 1:34 Sun.

I experienced pretty much everything mentioned above. The tires felt very similar. I think the larger contact patch on 315Rs made up for the grip difference of the smaller, softer A6s...

-I did notice that the A6s came to life a lot faster than the Rs in the 60* weather.
-The As had better brakes' from start to finish.


The problem with tracking is tires. Vipers eat tires....period!!! That simple...

I have been doing something that I believe helps tire life....IMO. I rotate one set of tires/wheels with another set after every 3- 20-30 minute sessions. In other words, I change out all four wheels and tires at lunch time.
The tires build heat during each session. I noticed that the tires would would start to roll rubber off a lot faster during the afternoon sessions. So I started rotating a second set of tires. Not only were the second set of tires at their best (fastest)for the afternoon,
the tire wear on both sets were a lot less in the long run....

The problem, as mentioned above, is not wear but the number of heat cycles. You might have plenty of tread but the rubber is worn out.

Not much you can do about that.....

 

[treesnake]

FWIW....This was taken from the Hoosier tire website...

6. How do I know when it is time to replace my R6/A6 competition radials?


Located on the tread surface of the tires are small divots or holes. These divots are called tread depth holes and are used to measure the wear of tread. Tread depth is usually referred to in 32nds of an inch. A brand new tire should measure 4/32 of depth in each of the holes. By keeping track of the number of laps on each set of tires and measuring the depth of tread, you can calculate how much wear is left in the tires. When the holes are completely flush with the tread, it is definitely time to change to a new set of tires. There is tread rubber under the depth hole and the tire can continue to be run, but the driver must be aware the performance level will be at its lowest. When this rubber below the depth hole is gone, you will then see the first layer of cords. At this point, the safety of the tire is now compromised and the worn tires should be replaced.
The driver must be the ultimate measure of when to replace the tires. There might be measurable tread depth on the tire, but the performance (grip or handling) of the tire might be low. To get the most wear out of your R6/A6 competition tires, be sure to rotate front to rear or side to side after an event.



Theres some pretty good track tire info here...

https://www.hoosiertire.com/rrtire.htm

 

[SCLSSRT10]

Guys, there is no cut and dried rules for tire replacement but the exerpt from Hoosier above is VERY good. If you are getting 20 heat cycles out of A6's & R6's you guys are luckier than I am. I use R100's on my car and they are basically junk after 6 heat cycles. Any body that tries to get 20 heat cycles out of Hoosiers is putting them selves and other drivers at risk of serious injury. The driver is the best judge of tires and their grip. If they are starting to loose grip get them off the car. Tires are cheap in comparison to crashing a car due to thinking the tires are still working.

Just my humble opinion, but what do I know.

 

[TowDawg]

For faster times and 110% driving, I completely agree. I got a lot of cycles out of my R's and could definitely tell the grip was going away, but they still gripped better than my street tires.

 

[bluestreak]

Guys, there is no cut and dried rules for tire replacement but the exerpt from Hoosier above is VERY good. If you are getting 20 heat cycles out of A6's & R6's you guys are luckier than I am. I use R100's on my car and they are basically junk after 6 heat cycles. Any body that tries to get 20 heat cycles out of Hoosiers is putting them selves and other drivers at risk of serious injury. The driver is the best judge of tires and their grip. If they are starting to loose grip get them off the car. Tires are cheap in comparison to crashing a car due to thinking the tires are still working.

Just my humble opinion, but what do I know.

Depends on the type of HC. There are 4 types, Auto-X, DE, TT and Race. Auto-X is obviously the easiest on the tire, which is why they can get 30-40-50 runs out of a set of tires. TT is next because most times you get probably 2-4 laps and off the track, barely more wear than an Auto-X. DE if you drive the full session, even though slower is harder on the tires, tires getting hot and staying hot wear them out faster than heat up and cool down quickly. And obviously racing is the hardest.

I still have A6's with 24 HC on them (fronts only, rears corded) that did pretty drama free 1:28's at Road Atlanta. They have plenty of tread on them and are completely safe. Having to exercise some car control occasionally is not hazardous IMO, but should be practiced regularly by advanced level drivers and racers. It's still a lot more grip than driving in the rain, which is also great for car control. You'll never get 20 races out of tires, but 20 3 lap time trials? Heck yeah. At the end of the day it likely comes down to the total number of laps driven. In a 40 minute race you may get 24 laps or so on an average track. I can run 6-8 Time Trial sessions or HC for that one race and the tires will still be fresher after those 8 HC than that one race. A DE driver will fall somewhere in between at probably 9-12 HC because they aren't likely pushing the tires as hard but for longer periods.

And finally, caring for the tires, you can't do much of that while racing, but even during DE, I do 5 lap stints then a cool down and/or drive through pits laps. Let's brakes, tires, engine, tranny and everything else cool down a bit.

Just my experience, others may differ.