[BoostJunkie]

That is the question Anyways, I'll be switching to R-comps for next season and based on all of the info I've gathered I think the RA1 will best suit my needs. I'd like a tire that I can drive on to and from events, and that will have very good grip in both dry and wet conditions. The question is, what tread depth should I run them at to maximize dry performance while still keeping them safe for wet conditions? Would shaving to 6/32 be enough to sufficiently eliminate tread squirm or do I need to go to 4/32? Is 4/32 too shallow to be safe in the wet? This is primarily just for HPDE, although I may do a time attack next season as well.

[srascal]

6/32 or don't shave them at all if you're using them on the street in the rain. Its still not as bad as people make it out to be, but it its your first time on r-comps play it safe. Ive honestly run Hoosier R6's in RAIN, and I mean like a downpour, and they weren't all that bad, and thats on a rwd car. Still for just a hpde car, and if this is your first time on r comps, run em full.

Theres alot of truth to the statements about r comps not being forgiving, everything happens much quicker, once the car gets loose its definitely tougher to regain control. I learned the hard way a few times
Thats why id probably progress into them and run them full depth or 6/32 for a season, or half a season. You could always buy a set at full depth and then once you become comfy with them, buy another set and shave them to say 4/32 and save the other set as rains

[spazegun2213]

dont, not worth it. you have a 3800lb car (with fuel, you and instructor). you are going to run though RA-1 faster than most people. You will need to get used to them as well, so by the time you feel good on Ra-1's you'll be at their sweet spot.

[smurfm3]

Depends on how you drive.

I would not drive on un-shaved RA-1's in competition. It's a waste of time. There is a lot of tread squirm. A 4/32nds shave is worth at least a second.

However, for open track events shaving it's your call. They will perform better when shaved, but if you want longer life, shaving is clearly counterproductive since you are literally cutting down the life of the tire.

[BoostJunkie]

Yeah these will for the most part be just for HPDE, no serious competition. The main thing I was worried about is that I have heard that running them at full tread can both reduce their overall life (chunking can occur with heavier cars) and make them useless by the time they are a little more than halfway worn due to too many heat cycles. Is there any truth to either of these?

[smurfm3]

Originally Posted by BoostJunkie

Yeah these will for the most part be just for HPDE, no serious competition. The main thing I was worried about is that I have heard that running them at full tread can both reduce their overall life (chunking can occur with heavier cars) and make them useless by the time they are a little more than halfway worn due to too many heat cycles. Is there any truth to either of these?

There is some truth to both.

Chunking occurs when you are overheating the tread surface. Most people who "chunk" their tires should be on shaved rubber. You need to be driving at the limit to overheat your tires at full tread depth. Camber definitely helps this one. It all depends how fast you are and how hard you are on your tires (they are not always synonymous-- if you are driving the wrong line you can be even harder on your tires than a faster guy driving casually on the correct line).

At full tread, you will get more "life" out of them but they will be slower than a comparable shaved tire at, say, 2/32nds if you wear them there than if you had them shaved there. However, the difference is so small that you it's almost negligible. In other words, the Speed World Challenge guys who run RA-1's might consider tossing them after a couple sessions, but you or I have no reason to until they're worn out. RA-1's are an incredibly stable compound throughout their life compared to, say, Hoosier R6's or Kumho V710's which will drop off noticeably. However, in my experience, they get better as they get closer to zero tread. To put this in perspective, I would rather race on 2/32nds rubber that started at 4/32nds than new 4/32nds shaved rubber (even though the 2/32nds has more heat cycles on it). One amusing fact is that the SCCA runoffs drivers from my region ordered 3/32nds RA-1 shaves from my local tire shop.

Another good thing about RA-1's is that they're no longer directional once the rain tread grooves disappear. You can have them flipped on the wheel so that your inside becomes your outside and vice-versa if you wear out the outsides too fast. Personally, I have not "flipped" my tires because I think that it's not worth the cost of mounting/balancing, but once my tires get to that point, they're like 2/32nds on the inside and 1/32nd on the outside. In other words, I could get another couple sessions out of the tire, but at $130/tire, I might as well just buy a new one ($20 for flipping in labor). However, STi's are somewhat camber challenged unless you go to an aftermarket suspension, so the difference might be great enough to justify it depending on your situation. Just letting you know that it's possible...

Sean

[flatthump]

Originally Posted by smurfm3

Depends on how you drive.

I would not drive on un-shaved RA-1's in competition. It's a waste of time. There is a lot of tread squirm. A 4/32nds shave is worth at least a second.

\
Straight up what I was going to say. When I was a newb I ran them unshaved on a 72 911sc. You gotta learn somewhere.

There is quite a bit of talk on all the porsche forums on the RA1.

[stretch]

Originally Posted by BoostJunkie

That is the question Anyways, I'll be switching to R-comps for next season and based on all of the info I've gathered I think the RA1 will best suit my needs. I'd like a tire that I can drive on to and from events, and that will have very good grip in both dry and wet conditions. The question is, what tread depth should I run them at to maximize dry performance while still keeping them safe for wet conditions? Would shaving to 6/32 be enough to sufficiently eliminate tread squirm or do I need to go to 4/32? Is 4/32 too shallow to be safe in the wet? This is primarily just for HPDE, although I may do a time attack next season as well.

In my experience, dry traction increases about the same time wet traction decreases- that is, at the time the smaller tread blocks disappear and you're left with a ribbed slick. That happens at 4/32nds as I recall.

Since RA-1's last for a zillion heat cycles and, generally speaking, they love heat, I'd not recommend shaving them unless you really need to be competitive on them immediately. They hold up pretty well and will continue to get faster as they wear.

[BoostJunkie]

Ok that's all I needed to know. I could really care less about getting an extra half second out of them by shaving, my main concern is longevity. I'm running -2.5 camber up front, along with substantial spring rates and swaybars so I think that should help prevent uneven wear and chunking. It will also save me some money not having them shaved. I'll probably do one more event on my RE070s in March and then they will be garbage, so I'll switch to the RA1s. Thanks for the advice everyone!

[smurfm3]

Originally Posted by stretch

In my experience, dry traction increases about the same time wet traction decreases- that is, at the time the smaller tread blocks disappear and you're left with a ribbed slick. That happens at 4/32nds as I recall.

Since RA-1's last for a zillion heat cycles and, generally speaking, they love heat, I'd not recommend shaving them unless you really need to be competitive on them immediately. They hold up pretty well and will continue to get faster as they wear.

Correct. They lose their wet tread blocks at 4/32nds. They lose their outer grooves at 2/32nds and finally become completely slick at 0/32nds.

[spazegun2213]

Boost, you'll probably want a set of rains if you go the R-comp route. I'll run full tread RA-1's as rains next year, and shaved/worn RA-1's for the race.

[BoostJunkie]

Well the whole point is that I want a single tire that can run in both the wet and the dry. I figure that if I run the RA1s at full tread, by the time they wear to the point that they can't be run in the rain they will have about as many heat cycles as they can take anyways so I will just replace them.

[spazegun2213]

Originally Posted by BoostJunkie

Well the whole point is that I want a single tire that can run in both the wet and the dry. I figure that if I run the RA1s at full tread, by the time they wear to the point that they can't be run in the rain they will have about as many heat cycles as they can take anyways so I will just replace them.

ROFL! then you will want to sell them to me! RA-1's only get BETTER as the tread decreases! trust me, I've not seen them heat cycled out until they are practically cording. Mav1c runs his ALL the way down, as do all the SM racers i know, and the 944 racers as well.

Bottom line is, you can't have both a Rain/Dry tire. Once you go to R-comps you may as well get another set for the rain.

However, if you want to sell me cheap RA-1's at their prime for cheap, by all means let me know!

[Mykl]

Have a look at the Nitto NT-01.

[spazegun2213]

Originally Posted by Mykl

Have a look at the Nitto NT-01.

even at full tread i would not recommend those in the rain. I've been on these tires and while they are amazing, they get to their sweet spot really quickly, and with virtually no tread.