[seanblurr]

There have been a lot of great tire discussions in this section recently, ranging from longevity to a faster lap time. In one of the longer ones, the Toyo RR had been discussed by myself and Cem. He has a very recent thread on his opinion of the tire compared to a G3R, both in 19" square sizes. I've gone a step further and will be attempting the Toyo RR in 18's.

For reference, the wheels are:

18x11 + 11 (with a 3-5mm spacer)
18x12 + 41

The tires are:

Toyo RR 305/35/18 and 345/35/18

The goal here is to find a tire that is equal in, or great in performance than the factory G3R but also one that lasts longer than 5-8 heat cycles without the dreaded inner cord that a lot of ZLE owners face. An impossible goal, perhaps.

I've been through many different tires including; Stock Goodyear G3R, Nitto NTO1 (315/30/18, 335/18/30 & 315/30/18 square), Pirelli DH slick take-offs (295/680, 305/680, 315/680 in both 18 and 19"), Hoosier R7's in stock sizes, Nankang AR1 (315/30/18) in an attempt to find that all-elusive tire. Each has had its benefits, but none, in my opinion, has come close to being such a good overall tire like the G3R. Thus, I have stuck with the stock tire for the most part.

This leads us to the RR...

The Nankang AR1 was a stellar tire, but the car was not happy with a 315 square set up. If you attempt to run with all the nannies off, the car is spectacularly loose. if you attempt to run in PTM:Race, the vehicle's electronics flip out because of the square diameter (IMO). From what I gather, for the TC/Stabilitrak to function properly, there needs to be a certain % difference between the overall heights of the front and rears. Too little, it thinks the rears are spinning and engages far too often. Ive heard talks of the car engaging ice mode with square tires, I never had that issue.

So, I started to research the RR. It came in a few different 18" sizes that I *thought* might work, and also allow for a decent, but not too much(I hope) % difference in diameter from front to rear. This is how I ended up with the current tire sizes. Yes, a 305-345 is a rather large difference in width, but there were no other options.

I hated the NTO1 because it had a soft sidewall and never felt great on the heavy Camaro. It's a concern with the RR's as they are very similar tires, but I'm hoping with a proper set-up and tire pressures they will be ok. Because they have a 35 series sidewall, I expect the tires to feel softer than the stock G3R's, but I hope with proper pressure they will be tolerable.

I've been reading a lot about and talking to tire guys about the RR's. There is a consensus that these tires are actually better at HIGH pressures, like, 41-42psi hot pressure. Especially with a car this heavy. Those are going to be my starting goals, at least.

In terms of set-up, I strayed from GM's recommended alignment this time around and let a race shop/team based at Sonoma Raceway handle it for me. Yes, it's not a race car, but I wanted to try something new from people who know what they are doing.

Initial alignment specs:

-3.4* camber front
1/8th toe out front

-2.0* camber rear
1/16th toe in rear

Everything here is initial and has NOT been tested. Expect things to change.

This will never be an apple to apple comparison because I have added some aero prior to last time out on the G3R's. So hopefully it'll be quicker!

Here are some pics, which is probably what you all want anyway.

[TrackClub]

Nice! Looking fwd to your reports Sean.
And thanks for the info! Cheers!

[TrackClub]

Two more musings from me, Sean:

1. My buddy with a ZL1 corded G3Rs beyond the belts and down to steel carcass in 2 sessions with 3.5 camber
So, it will be interesting how the RRs do.

2. You'd give up a bit of pace, but maybe still be the fastest car given on your wheeling skill, if ya tried G3s on stock 19 rims. And likely save big on cost. Might be worth trying?

[Ummpwr]

With out a doubt that looks really good!

Alignment specs all sound good for a typical rwd set up. I'm also curious to see how the front camber and tire wear balance goes.

Im also searching for a good 18in track tire option. Although on a SS1LE. So I'm curious on your opinion. (I'm leaning towards pzero slick take offs)

[TrackClub]

Originally Posted by Ummpwr

With out a doubt that looks really good!

Alignment specs all sound good for a typical rwd set up. I'm also curious to see how the front camber and tire wear balance goes.

Im also searching for a good 18in track tire option. Although on a SS1LE. So I'm curious on your opinion. (I'm leaning towards pzero slick take offs)

That's what Provoste ran on his SS 1le very successfully. Zero mods except strut grinding for (i think) 2.9 camber and Apex square rims. Having said that, he also loved ZLE rims and G3Rs Oh, and he also loved stocker G3s )

[RUQWIKR]

Stance looks great!

Not to hijack the thread regarding the tires, how much improvement was seen with the new aero on 3R's or whatever you have data on? Look forward to your thoughts on the tires.

[cirpower]

seanblurr - awesome how you are sharing your knowledge with us, thank you for that! Based on all your feedback I decided to go with the 3R tires in ZL1 1LE sizes on my "normal" ZL1 for the track "work". Keep us posted please.

[rickybobby]

Thanks for the update Sean. I’ll be curious to see if the toe-out up front will help with the inside cording. Most cars would be worse with toe out, but there’s definitely something different about our camaros that I haven’t had the time to get to the bottom of. The inside cording seems to be worse for me at Laguna so I thought it might me the T2 brake zone chewing them up, but I don’t have any true data to prove that theory.

[seanblurr]

Update as of 5/26 after 1 event:

Verdict? Meh.

Going in with the above-mentioned setup, with a first session goal of 44psi hot I immediately noted a lack of front end grip. This unfortunately, would remain for the entirety of the day.

I will do my best to explain this is in words because the handling characteristic was very odd. If I was not under power at turn-in, or attempted to feather/throttle steer the car, it would push like a mad man with absolutely no grip upfront. If, on the other hand, I aggressively turned in and was immediately on power at turn-in, at the apex, and through the exit, the car miraculously was much more planted and neutral.

This jekle and hyde like handling certainly bred a lack of confidence in the car. There were a few times where the front just completely went away from me and it understeered right off track. I had to drive very differently.

Pressure changes

Pressures, you might ask? I started with 44psi hot target, dropped to 40psi, and then 35psi. I ended up around 35psi front, and 38psi rear. It felt better, but nowhere near it should. If I had another session, I probably would have attempted an extremely high front pressure again.

Aero

Aero, maybe? While this is the first event with the APR wing and front splitter, I did an event a few months ago with just the APR wing on stock G3R's and the car felt pretty good. hardly any push. Unless the splitter is F'd and causing a ton of lift, I don't think my experience on Sunday was related to aero.

Tire size

The other obvious is the tire sizes themselves. A front 305 vs. a rear 345. It's not a crazy difference to stock, but perhaps that big old meat in the back is really just too much for the front.

PTM:Race

Another thought, PTM:Race mode and the effects of a non-factory tuned tire. I will be honest, despite whatever experience I have on a race track, I generally leave this car in PTM:Race. I'm not trying to prove anything and I prefer the fail-safe. With that said, and not knowing the intricacies of how the system works, could a slightly off-size tire combo cause TC/Stabilitrak to falter and increase understeer? I did notice my rear caliper temps were 100* higher than fronts. I turned everything off mid-session only to get the checkered half a lap later. This will be something else I try next event.

RR v. NTO1

I've experienced a similar handling characteristic once before, and it was with the Nitto NTO1's. It was something at the time I attributed to a too-soft sidewall, a problem I don't think the RR has, judging by the sidewall wear. It is a bit of a coincidence as these tires share a lot (same parent company). Perhaps there is just something with the carcass of these tires that can't handle this big old car. Or, frankly, maybe the tire is just so different than the G3R, it really needs just needs a new chassis set up to make it work.

Lap Times

To throw some numbers out, during my first session out, I had one lap that came within 4 tenths of my STOCK PB. Throughout the day I average about 2-4 seconds slower than this same PB. Admittedly, the track was pretty green as this was the first event held in a few months and it was about 80-95* on Sunday. Comparing simple speeds at certain points, they were either equal or a few MPH slower than the PB lap. Not what I would expect on a fairly high-speed track with the addition of aero.

[rickybobby]

Thanks for the details as usual. Did you happen to take any tire temps?
Also, how did the front tires wear?

I can’t wait to get back out to Laguna in June. I’ve been having serious withdrawals..

[Ummpwr]

I would definitely be interested in tire temps to determine if you had too much camber.

Seems like if you had a way of moving the alignment specs back to your previous good setting with no other changes and see if your understeer changes.

Possible bring another set of wheels with g3rs to swap and see if it is a tire related issue?

Could you adjust your rear wing to more flat so the front and rear balance is more even?

Just some ideas

[TrackClub]

Sean, the best way to test the aero is to throw your stockers back on and see what the corner entry balance is like.

BUT from what you have described, including the fact the car felt ok just with a wing and no splitter id suggest you need more aero in the *rear*.
This is mainly based on the above *and* the fact the car would turn in if you added power (which would transfer weight to the rear and lift the front). This to me means that the fronts were way over worked and sliding until you moved the weight off of them. More aero in the rear should balance this condition and return the balance to neutral.

As far as PTM Race: Stabilitrak is fully OFF in this setting and only TC (in its least disruptive mode) will engage on EXITS only. So in effect, corner entry and mid corner phases while running PTM Race is the same as running all off. Only exit is helped by PTM Race.

How was the tire wear? Cheers!

[glamcem]

Car looks great

I am surprised to hear that you found the NT01s sidewalls soft.. On the contrary, they're typically known with their stiff sidewalls (as well as the RRs). That's exactly the reason why I preferred NT01s (305/325s) with my previous 1LE, Trofeo Rs were awful for instance. I would say Trofeo R, Cup 2 and SC3Rs all have slightly softer sidewalls than G3, Bridgestone tires (in general), RR or NT01s.. again assuming they all have similar profile (30 vs 35)

One thing to come to mind is, GM might have fine tuned the ZLE as they did for the C7 Z07 packages for the specific tire with very stiff suspension so maybe using a stiffer sidewall tire feel awkward. Also for the RRs, 35 profile tires (especially front) might have felt a bit baloony maybe? Not to mention that there's no ideal size for your car so technically you downgraded the front size (by a huge margin since even the 305 SC3Rs are wider than 315 RRs on the same 11" wide wheel and 305 RRs should be even narrower) while adding tons of rubber in the rear (as well as the added down force with the new wing).

RR compound itself is very good actually it's slightly better than NT01s and in between them and the R7s. It's too bad you cannot fit 315 or even 325 RRs since that size doesn't exist. I think it would help a lot. It definitely did for me . They're of course still slower than the SC3Rs but the prices are very good and they typically give 20-25HCs . I don't know about the SC3Rs just yet because I keep destroying way before than they HC out

Also on a very hot day, SC3Rs will be more consistent an faster of course.
I would target the hot PSIs at around 32-33 ( so basically start at around 26-27PSI cold) and release some air after the first session when they hit 34-35psi ..I do this all the time then it stays at around 32-33 PSI on the other sessions. This will definitely yield better lap times but on the other hand it will be less consistent than targeting 38-42psi ..so pick your poison. Since we typically destroy the tires way before than they HC out, I wouldn't too worry about the longevity .. Toyo recommends those hot pressures for longevity and consistency . When the RRs fall off because of the lower target pressures, it doesn't fall immediately ..it still gives you a good bit of a feedback.

I will try the 315 RRs on a better/cooler day. I improved my PB at the Ridge yesterday and did shaved about 1.2 seconds with 305/325 SC3Rs previous PB best was with 305/325 NT01s..to be fair though, it was in the early sessions with NT01s (3 years ago) and yesterday when it was warmer..that alone should make a 1-1.5 second difference there