engifineer

The 615k+ was very lackluster when I ran them. Cheap and last a long time. Peak grip is at room temp, then goes downhill from there I honestly would probably go RS-4 before the 615's.

B serious

Lol I get the same opinion from everyone about the 615K+. That they're barely up to the task.

But man every time I've used them, they've been killer, considering the price. Maybe just driving style or setup differences. Or maybe its just managing expectations. I never expected them to be on par with the fastest 200TW. But $600, they last forever, and they're just quick the whole time.

B serious

BTW, RE71RS are $1044 out the door today at Costco. We have a 7.5% tax rate here.

It seems to be a better price than anywhere else. But I'm just gonna burn these RT660's to the filter before I go buy anything else...even if it is more expensive to upgrade next year.

engifineer

I first was around them when the then new SSC class (BRZ/FRS spec class) had to run them. Drivers hated them because they had to spray them between every single run even on cool days to keep them in their peak grip point. They do not fall off a cliff past that point but just are never at their peak grip once they warm up. However, for these purposes (HPDE) likely not a concern over price and wear. I ran them for one season as an HPDE tire and had no real complaints, but the RS4 was faster for me and was also cheap. But I then went to the 660's which were noticeably faster than the 615 of course. I planned to start TT this year and still hit up some autox which is why I went with more competitive RE's this time around.

Jun118

Don't cheap out on tires. you have two tires that are obviously not suitable for tracking (one worn out, one so-so which mean it's probably worn out enough that you should replace them but can probably squeeze some regular mileage out of them...).

Just buy a pair of new tires and moun them in the rear and mount the used mint ones up front.

It's going to end up costing you a lot more than two tires just to "save $500" when your car ends up on the wall after losing grip.

engifineer

He has been at this for a long while, I am sure massively worn to him is still well within safe limits. With tires within safe wear limits.

I try to rotate mine front to back between track events to keep them relatively even.

On that wear though, I am curious. I tend to wear the rears slightly faster on this car. I assume mostly driving style and setup. And track too. When I was running a very tight, small track (driving course) with short straights and tons of turns relative to straights, I REALLY wore the rears faster I assume due mostly to digging out of tight corners and heavy trailbraking to rotate into the corners. On larger tracks mine wear more even but slightly more in the rear. I assume that the longer, more sweeping turns are going to put more strain on the fronts vs more tight sections, and the local track I ran for the last couple of years has a few tighter sections in it. So I guess this makes sense.

Chuck S

Not sure what wheels and tire sizes @B serious is running. OEM rear and front wheels are not interchangeable due to spindle differences so tire "rotation" is limited to changing to the other side of the car on the same axle -- as is the easiest scenario here. Moving front to back requires dismounting and remounting the tires. I believe the OEM rear wheels will fit the front axle but not vv.

Differences in the spare tire diameter means it should only be used on the front axle to avoid damage to the Torsen differential: Get a rear flat ya gotta pull the front wheel too so the front wheel can be placed on the rear axle and the spare on the front.

-- Chuck

Jub

RT660s are just not a quality product, IMO. They were fine when they were significantly cheaper than other 200TW tires and close to pace. At that point, I would recommend them to people as a good, affordable tire. Price has gone up and they still have the same quality issues that they had when they were a few hundred a set cheaper than other 200TWs. That includes delaminating, heat cycling out, inability to deal with heat, not as fast as other super 200s. It is unacceptable to have that many significant quality issues when they are as expensive as the competitors that do not have those issues.

V730s have a different set of downsides but are a quality product. Biggest downside is that I'd hardly want to drive them in the wet, on track, when new. They're an awesome lapping tire if you have a different rain option. They're really not that far off pace of the super 200s and can be fast for an entire session.

engifineer

I have still yet to see an actual case of delam on the 660's personally. Heard lots of talk and saw one pic that had some very obvious other damage present. Most of them had the visible line which was 100% the seam in the tread and caused no issue. Mine had it from event 1 and never had one issue with them. Everyone I knew that ran them had no issues with them. But I know some say they did so who knows. The friend of mine that is a tire guy also had never had a complaint of actual issues with them from his customers.

Mine were still running fine after I think 6 track days. Had not cyled out yet and still putting down consistent times. I just ruined 2 of them in a crash so never ran them fully to nothing.

Now, I will say I was faster on the Kumhos and I feel like they were more consistent from start of session to end of session. I also like the feel of the 730's better. A ton of complaints I saw on the 660s were people did not like the feel. Said they did not communicate well. I did not think they were as bad as some but I did like the way the Kumhos drove a lot better.

Jub

I've run a lot of SSC for the last two years. We've had two tires delaminate and become useless. It was on a rough surface with multiple drivers, to be fair. Have had them heat cycle out. We've taken way better care of them than I have my Yoks, 730s, or Stones. I've never been concerned about the integrity of those 3 tires but have with the 660s. Granted, I've seen more sets of 660s and they've been co-driven more on a SSC car more than the other tires on my STR car. I do think the 3-3.2 degrees strut front is harder on tires than my S2k is with 3.2-3.5 degrees front.

I am not confident that I could push a 660 on track for full sessions and not risk ruining it. A052s, I'd worry about a bit. 730s or Stones would be just fine. I just don't think the Falkens are a high enough quality product in terms of lap time, heat cycle-ability, and build quality to command price similar to the others. 730s are objectively a quality product and are cheaper. Stones and Yoks cost a little bit more than Falkens but I think they're worth it in quality and speed. I have reasons I could recommend the Yoks, Stones, or 730s but I don't see a reason to recommend Falkens anymore unless you have to run them in a spec class.