jwr9152

That I don't know, but I've run enough sets of them now to feel confident they like higher pressures, and that's held true at 5 different tracks in cold weather and hot weather. You are always going to run into personal preference, so I would play around with pressures and run what feels good to you, but I certainly wouldn't be afraid to bump up the pressure on the 660's and see how it feels to you.

welikethetrack

I run 4s’s, they literally last 3x longer than any other tire on the track in my experience.

in My experience the driver matters way more than the car/tires, so unless you’re in an actual race, the 4s will give you the most “fun per dollar” as well as change tires 3x less…

welikethetrack

I will say you lose some turn in and sharp scalpel feel on the 4s vs a cup2, almost the difference I’d say going from a gt3 to an rs of any given gen

TRZ06

I do not agree on the "tires don't matter much" part of your statement. Anything from Michelin has soft sidewalls, which you can feel when the car is loaded up in a corner. There is sidewall lateral movement that needs to be addressed with steering corrections.

With a stiffer sidewall tire, you can take a set and the car will not move around laterally.

It absolutely can be felt if you are carrying a good amount of pace in the corners.

lovetoturn

The 4S's or any other type of street tire can be prone to chunking on the outside edges if you push them too hard on the track. Have friends that have had this happen to them back in the day. On both the Michelins and OEM Pirellis. I run them on my Macan S and they are fantastic for me in that application.

welikethetrack

What's interesting is I have actually had this happen on cup 2's and even most recently the dunlop sport maxx race 2 more than 4s's or super sports

lovetoturn

Interesting, maybe they have toughened them up over the last 5+ years.

dc5s

I just mounted 265/35/19 and 295/35/19 rt660 on the @APEXRaceParts vs5rs 9 and 10.5 combo.

Front suspension has tarrett camber plates and rubbing issues sorted out at 3deg camber
Rear suspension has toe links and locking plates. Rear camber camber is 2.5 with 10mm shims added and there is some obvious rubbing in the rear. The wheels and tires stick out a little and the rubbing looks to be about 1" from the outside of the tire.

Has anyone encountered this? These are the sizes recommended by Apex on their fitment guide.

Zhao

I chunked my cup2's also, and have 5/32nd tread blocks on one side of the block and 0.5-1/32nd tread on the other side of the block. But IMO michelins hockey puck up pretty hard pretty fast so I could see someone with 'old' 4s's not chunk them just because they aren't gripping enough to generate anywhere close to the same heat they would if they were fresh rubber. I ran old michelin AS3's on my lead follow car with no negative camber and no amount of overdriving that thing caused them to do anything but wear the outside edges slightly faster than the inside; they just didn't have any grip to grab the pavement before they started slipping..... If those were new I guarantee they wouldn't have lasted 30 minutes driving like that let alone for a full race school.

For me I can go a year with HPDE's driving dot slicks and only go through one set of tires, so slicks or re71r's or similar tires designed to take heat well last much longer for me.

There is also obviously driver differences that makes a big difference. I know I have students who can bang around the whole weekend in something like a RS4 on skinny pirellis and no camber and not have any serious tire wear issues.

enduro

My RT660 continue to improve with heat cycles, up to 9 sessions with them now. Still figuring out pressures, think I'm going to back off a little & aim for around 33 to 34 PSIG hot. Also rode with @paffinity in his 86 on RE71RS that are nearly corded. Felt like impressive grip from the passenger seat. Ordering a set for my Miata, once it's running, will A/B test them throughout their life with same heat cycles SC3R, which are my current gold standard. Also had the local pro comment that the RE71RS are impressive in the wet, echoing what @85Gold said earlier in the thread.

lovetoturn

Wish they made a 265/305-19 setup in the RE-71RS for our cars. The older ones were my go to tires for my previous Cayman S in a 255/285 setup.

enduro

I will say that on my M, the RE71R (not 's') got greasy fast on a hot day, and the SC3R went much further before getting greasy on that car. Looking forward to comparing the -RS to my SC3R this summer.

edub

I just added a 10mm shim to the left rear side and it rubs right on the sidewall with 295's. Never had this issue before and I bet its the shim. I'm going to try and re-align, remove the shim, push the top plate in as much as possible in the bolt holes and raise the rear up a bit to reduce it.

I'll also consider reducing rear camber, it was -2 without rubbing and moving to -2.5 was what did it.

Could also go to a stiffer rear spring but interference is interference

lovetoturn

It is a fine balance between shim and ride height to get what you want without rubbing. Also 19 inch tires are shorter and you can fit a slightly wider but shorter tire in the same space as a 20 inch OEM one.

Twelve mm of shim, a couple of mm below standard ride height, with a 305/30-19 and everything fits fine with no obvious rub.

Of course a rear camber plate can solve all of this, like the ones from Immocar in Switzerland.

jwr9152

A 305 is coming out sometime this summer, so I've been told.

Forget if I mentioned here or another thread, but I run the RT660's in a 265/305 and I find it to be better then the old RE71. Both for lap time and consistency over an entire session. I did get a set of 255 RE71RS for the front and ran them with 305 RT660's on the rear one weekend. It upset the balance of the car and caused it to oversteer, which tells me they have more grip then the RT660's. Was still fast and I was almost 2 seconds faster then my previous PB at that track. This was with new RE71RS and a set of used RT660's. That same day I swapped the fronts for 265 RT660's which improved the balance of the car and went over a second faster and set a new new PB. Would have also been a class lap record, but i didn't have time to get my car dynoed before the event, so I had to run in unlimited. I say that only to point out that even though the RT660's were used they were obviously still fast and working well. If the RE71RS have that much more grip, can't wait to try a full set up. It ought to be real fast. May have to play around with setup a little to get the balance right going to a 255/305 setup, but ultimate grip should be up.